Hallo
I have never played PnP games, but I have played computer games based on DnD 2 (IE games), DnD3 (NWN1+2), Pathfinder Kingmaker and DSA (Realms of Arcadia, Drakensang). I did some reading about the basics of DnD5, but there are some things still unclear.
- Are alingnment restrictions gone?
None of the class descriptions talk about alignment. The text shows also no negative consequences for your actions, except when they talk about paladins breaking their oath. So can we have lawful barbariens, chaotic monks, evil clerics of a good god or evil paladins?
I really like the paladin concept from Pillars of Eternity. They are faithful warriors of any god or ideology. In DnD terms you could be a paladin of any god, as long as the god is willing to give a warrior some divine powers to fight for him/her. So a chaotic evil god gave an evil paladin unholy powers when the paladin made an oath to ruin good or lawful kingdoms and to kill and torture people who try to achieve good or lawful things.
- Does your hit chance improve as you level up?
In DnD2 your thaco improved, in DnD3 it was BAB. In DnD 5 I saw no hit chance increase except your profiency bonus improves over time and you gain stat points.
So a wizard and a fighter have the same hit chance if they have the same strengh and the same melee weapon they are profient with.
- Animal companions are gone forever?
- Is there any reason to take a fighter instead of a paladin?
Fighters get 4 attacks at level 20. Paladins get spells and lots of bonusses and resistences for themselves and the party, plus turn undead and empowering their attacks with divine power.
In DnD3 fighters got more feats than other classes and they had greater weapon specialisation and focus.
1. Alignment is for roleplay reasons only. There are no alignment specific prestige classes anymore, or any other restrictions whatsoever. When you hit level 3 of some class, you can pick an archetype, regardless of alignment or stats.
Some other restrictions are gone as well, no enemies are immune to sneak attacks anymore.
In case of Paladins, when you choose an order at level 3 you have to follow certain tenants. If you don't you lose your powers for some duration. This is in the PHB from 5e, though I don't know if this will be implemented.
2. It does through proficiency bonus that start at +2 and goes up every 5 levels up to +6 at level 20. You need to have proficiency with your weapons to get it though. Casters get the same bonus for target spells.
3. I think that a Ranger archetype gets an animal companion at level 3.
4. Paladins get only one extra attack, Fighters get up to 3. But Paladins can use divine smite to increase their damage in a way that completely removes the necessity for more attacks.
Fighters still get the most feats along with Rogues at 6, but they don't get weapon focus anymore.