If you absolutely must have these creatures in combat and only in combat, then your only option is to turn them into figurines of wondrous power like the Bronze Griffin (level 19) and the bloodstone spider (level 11) Note well, your blade spider has errata applied to it, so it may not be as useful as you think it is. They exist at every level (therefore, have them priced at the level of the creatures) with the text:
"Power (Conjuration) Daily (Standard Action)
Use this figurine to conjure a [creature] (see below for statistics). As a free action, you can spend a healing surge when activating this item to give the creature temporary hit points equal to your healing surge value."
Just note that their hitpoints should be significantly lower than a "real" creature's, to reflect their eternal nature.
The reduce beast ritual (level 7, Dragon 405) is almost what you're looking for, but as the beast takes a few turns to grow, it's not appropriate for in-combat use. It is reasonable to house rule a paragon tier version of it that works with literal pokeballs. Note that most rituals are designed to not be combat appropriate, so make sure there's a significant cost involved with this.
Beyond that, I'd recommend rituals for swapping things out before you go into a dungeon.
There are many options that exist for Arcane familiars, like the Safe Retreat (level 15), unfortunately, they don't work particularly well for more... "real" things.
I would use the Primal Grove, not least because it's one of my favourite rituals for moving armies around.
The primal grove ritual (Level 19, primal power) creates a persistent extradimensional space:
A grove generates enough food and drink to sustain its occupants and has a moderate, unchanging climate. If you move objects into a grove, they remain there when you leave,
So it's a great place to keep people. With 10 minutes (or fewer if you specialise) and 4k (which at the levels you're talking about is literally pocket change). The 10 minute casting time is handy because you can't pull it out during battle, which means it doesn't need to be balanced for battle.
Alternatively, if you read the hireling rules liberally, it seems to be viable to have a level-appropriate hireling (cost * 3 equivalent to sage) be able to cast specific rituals.
What you'll need, therefore, are 3 pairs of sending stones (level 11) and 2 ritualist casters. The follow the voice ritual (level 16) allows the caster to teleport to the location of the last activated stone:
You fold yourself and each ally you choose who is within 3 squares of you through a sending stone you hold.
The real trick is that there's a 24 hour use limit on pairs of stones and casters.
Therefore, there are two operations that you'll be performing: "sending" and "receiving" The sending operation has one pair speak to you through one of your personal stones, the first one casts follow the voice, teleports himself, his buddy, and your ally to you. They drop off the ally, collect whomever needs collecting, and the casting buddy returns.
The third pair of stones is for your fellow PCs. Sometimes, you'll want to teleport an injured companion back, and you'll need to home in on a PC's stone instead.
Yes, this build works, and it is strong.
I ran the numbers, and the average damage using your build and the -5/+10 feature gives you an average at level 5 of 22.8 damage per round (dpr). By comparison, a Great Weapon Fighter build with either the Great Weapon Master or Polearm Master feat deals an average of 18.7 damage at the same level. This build maintains a significant lead over those builds all the way up to level 20, for a total of 42.5 dpr at level 20 compared to GWM's 34.3 dpr.
However, the real difference between the builds is how the weapons work. Your crossbow build has the benefit of range, but the other builds get their own benefits. A Polearm Master has incredible control over the battlefield with their increased reach and many possible opportunity attacks, and a Great Weapon Master can deal much more damage if they get the chance to cleave through enemies and/or use opportunity attacks.
Compared to a caster, you'll probably beat them in raw damage, but casters can do a lot more than deal damage, so that's not saying much.
Best Answer
Never miss is hard to come by, but you can get quite a good attack at your level.
Attributes
For an Archer Ranger there is no reason not to put 18 before racial modifiers on Dex. If you are sure you never reach level 14, 17 is sufficient. Increase it every chance you get.
Attack: 6(half level) + 5(attributes) = 11
Race
Take any race that gives a Dex bonus. If you want to make sure you hit, Elven Accuracy and Heroic Effort (human) is great.
Attack: 11 + 1(racial Dex bonus) = 12
Weapon
Superior Crossbow has good damage and range, and great accuracy. It is a bit feat intensive, as you need Speed Loader, but at your level you can afford it.
Attack: 12 + 3(proficiency) = 15
Enhancement
At your level having a +3 Frost weapon is quite reasonable.
Attack: 15+3(enhancement) = 18
Feats
Crossbow Expertise is a must, depending on your DM and your minor actions, you might also need Speed Loader. Another feat is needed to get Combat Advantage as often as possible. If you can not convince your melee Leader or Defender to take Vexing Flanker, but they are good at tactical positioning, take Distant Advantage. Otherwise take Wintertouched for accuraty, as you have Lasting Frost for damage. Attack: 18 + 2(expertise) + 2(CA) = 22.
Hit chance
At level 12, an average Standard monster has an AC of 26, a Soldier 28. You can hit it with a roll of 4 and 6, respectively, 85% and 75%. It is quite good, especially combined with Elven Accuracy or Heroic Effort.
I assumed in all steps that you exclusively use Twin Strike, since that is the only viable choice if you really want to optimize your damage. As a Striker you should.