They're not the same game. While that seems obvious, many people take the lessons and assumptions from 3.5 and try to port them directly to 4e is a grave mistake. The best example of this are the early monsters which try to use player-available weapons and other player-assumptions to inform monster design. This has led to horrible monsters in early adventures.
It's a complex and digitally enabled game. Characters have remarkable and intimidating complexities in them. While it is certainly possible for an experienced player to make her character by hand, the digital tools out there allow for a much smoother experience. However, players tend to forget things that don't appear on power cards, so that while a digital character sheet is an excellent choice to start with, players should hand craft their own sheets, their own cards, and their own checklists. I personally recommend power2ool.com for power cards, and google docs for making a checklist. (Rationale behind the checklist: powers are hideously complex. No really, people have 3 actions a turn and only 3% of powers analyzed above only do damage. By working through the tactics ahead of time, players can actually engage in combat without trying to figure out their options as perfectly spherical adventurers).
Loot is part of character, not a reward per se. 4e features a ... pretty decent simulacra of advancement through bigger numbers without... actually changing any fundamental relationships between accuracy or damage. There are pretty useful guides (random or list, depending on which DMG you're using) in the DMGs for loot to drop, and players should generate wishlists, or you should use intrinsic bonuses. But don't monkey with the math without thinking about the implications of that. More difficult encounters should come from the environment, higher level monsters... not depriving the characters.
Don't simulate. 4e is a game of combat-as-sport. Players don't have scry & die, save-or-lose, or any of the other... quirks of 3.5's combat-as-war. This presents something of a problem when players spend too much time planning ahead. Figure out your general policy when your players choose to engage in combat-as-war and tell your players about it. If you're OK with players facerolling an encounter because of prior planning, make sure they know that you won't negate their successes. If you're not, make it part of the social contract and make sure your players won't be adversely impacted by not planning.
The party is the fundamental unit of interaction. Make sure that your players have a functioning party. The difficulty of the game is determined by how well the party works together. A good party will triumph over remarkable challenges, a bad party will have trouble with equal level challenges. Tailor the challenges to the party and allow them to plan and communicate and roleplay.
The quality of RP is a function of the DM. If you don't reward roleplaying, you won't get any. Combats can certainly be taken in a boardgamey feel or in an RP feel depending on how the DM guides them. Verbal rewards ("Cool!") are fine as is verbal description (but reduce the number of enemies accordingly, or their HP, to compensate for the increased time that combats will take.) I prefer both verbal acknowledgement and to give out a floating "+2 bonus" that they can use in the same encounter.
Skill challenges present interesting challenge to the DM Scenes are no longer resolved by "roll diplomacy" ... instead it can sometimes turn into "everyone in the party roll diplomacy many times." You need to figure out your own philosophy towards skill challenges and a way that they will be fun and interesting to your group. Many many thousands of words have been dedicated to them and I still haven't found a framework I'm happy with.
Instead of looking for fantasy in the modern-fiction sense, I'd start by looking under collections of fairy tales and folk tales. They're widely studied, freely available, and often well-suited to being retold in generic forms or other settings. And this is the source material from which all modern fantasy draws. I recommend looking for children's versions; these tend to simplify the tale down to the most basic elements - important if you want to get the story smoothly worked in to your roleplay.
A few sites to get you started:
You also can't go far wrong with Perrault, but of course those stories are now so well known it's hard for your audience not to be too far ahead of you.
Failing that, any fantasy short stories collection is bound to have a few, with a little adaptation. (The Baen Books free ebook library is a frequent go-to source of mine for light reading and new universes, but less suited to your needs.)
Well, Pathfinder uses largely the same ruleset as d20 Modern did, which while not the best modern gun system ever is far from the worst. Here's how to get the most out of it for a firefight.
To make anything like a realistic gunfight, people have to be concerned about being shot. This means that people should have few hit points, and that guns should do a lot of damage. Keep levels low and advancement slow. Consider doing something like the E6 variant rules that cap normal level advancement. Do NOT use the piddly official Pathfinder gun rules. Use ones like the d20 Modern rules Brian linked - 2d6 should be minimum ever for a gun. If you're at a reasonably low level, 2d12 from a .357 Magnum is terrifying. A crit there can one-shot most characters of levels 6 and under. You can also try the d20 variant vitality/wound system. Oh,and remove AoOs for using a gun in melee.
Pathfinder has the same cover and concealment rules that all d20 variants have. Learn them and use them, especially partial/improved cover. Same with the terrain, vision and light, conditions, etc. rules. You need to become really familiar with most of those kinds of sections and be applying them all the time, not on an exception basis. Heck, even if you're shooting someone in the same motel room, do you see ALL of them? Or is enough of them behind a bed, tv, etc. that at least a small cover bonus is merited? You should be using Perception an awful lot. One of the distinctive elements of firearm combat is how hard it is to see all your foes and everything that's going on. Exert these rules to the utmost - and when in doubt, give defensive bonuses. If cover and concealment bonuses are so piddly compared to to hit bonuses that no one cares, they won't take cover - make sure defensive stuff helps. It's OK for most shots to miss. Strongly consider not sharing much information with the PCs, like whether they hit a foe or not (let them have a Perception check, but don't just say "ah yes you hit and do 10 points of damage" or "he is definitely down and dead") - this forces them to be careful and double-check what's going on.