The solution is for the PCs to experiment with each of the spells to get a better feel for how useful they are during an actual game. Once your players have a chance to experiment a bit with the spells they have available to choose from, the task of deciding which ones are worth picking will be significantly easier. Also, as the DM, you may wish to reward good Intelligence or Wisdom checks made by the PCs during research activities by giving them suggestions as to which spells might prove useful over the course of the adventure. For example, if you're running the Lost Mine of Phandelver, you may wish to reward a player who spends time researching dragons that Green Dragons are masters of poison, so a Protection from Poison spell may be worth the Cleric's time to have prepared.

Because many of the 5th Edition mechanics and spell changes will likely be new for many players who did not participate in the playtest, the Adventurer's League Player's Guide also offers a nice solution to this problem. During levels 1-4 (the first major tier of gameplay) you can rebuild your character at the end of an episode or an adventure. This will allow you to try out low-level spell combinations without fear of being stuck with poor choices. Encourage low-level players to pick spells that sound cool and appear useful but not to fret over making bad choices because at the end of the session they can retcon their choices anyway.

It's worth mentioning that this should be significantly less of a problem for the Cleric, Druid, or Paladin because they each automatically have access to their entire class's spell list. If they wish to change the spells they have prepared, they can do so at the end of a long rest.

Lastly, note that some spells (those with the ritual tag) can be cast as rituals. This means the casting time is increased by 10 minutes (to prevent them from being used in combat), but the spell doesn't use up a spell slot. Bards can cast any ritual that they know. Clerics and Druids must prepare their rituals just like any other spell they plan to cast, but Wizards can use their spellbooks to avoid preparing rituals ahead of time. Warlocks who take Pact of the Tome have an invocation option which gives them the ability to learn every class's rituals in the same way as a Wizard. There is also a feat (Ritual Caster) which can grant ritual spellcasting to the other classes. This too will allow your players to try out more utility spells that may or may not be useful without making them sacrifice more pragmatic options like combat spells.

No.

The fifth edition of D&D is effectively an entirely different game from Fourth Edition. While there are some similarities (roll a d20 and add stuff), they tend to be pretty superficial.

Even when names are reused, the concepts underlying the name can be entirely different. For example, a saving throw in Fourth Edition is a difficulty ten roll without modifiers at the end of your turn. In Fifth Edition, it is an ability check usually made at the time something is first affecting you.

With that being said, there is a great deal of overlap in terms of the world (sort of, it's complicated), flavor, and "soft" advice between the two systems. You could certainly use the situations, locations, and characters from Fourth Edition to inspire the same in a Fifth Edition game... You'd just need to throw out all of the Fourth Edition mechanics and rebuild them in 5th edition terms.