Ok, tell me I haven't been doing it wrong ... So I got a 3rd level fighter and I multiclass to ranger ... would I add +1 to my base Fortitude or would I add +2, as per the 1st level Ranger? this rule seems kinda confusing to me.
Second: animal companions as they gain level they get increased ability scores, is there any reason why I would be forbidden to add the scores to Intelligence, thus having a speaking wolf at 20th level; and by the same token any reason why I could give him a skill like perform singing?
For example, let's say a 5th-level fighter decides to dabble in the arcane arts, and adds one level of wizard when he advances to 6th level. Such a character would have the powers and abilities of both a 5th-level fighter and a 1st-level wizard, but would still be considered a 6th-level character. (His class levels would be 5th and 1st, but his total character level is 6th.) He keeps all of his bonus feats gained from 5 levels of fighter, but can now also cast 1st-level spells and picks an arcane school. He adds all of the hit points, base attack bonuses, and saving throw bonuses from a 1st-level wizard on top of those gained from being a 5th-level fighter.
So if you go fighter 3/ranger 1 You have a +4 BAB, +5 fort, +3 Ref, +1 Wil
If you continue into ranger you simply add the bonuses as they go up, so at fighter 3/ranger 2 only your BAB and Reflex save would go up
Not that familiar with AC's so I will check it out, but someone will more than likely answer that before I get back lol
So I got a 3rd level fighter and I multiclass to ranger ... would I add +1 to my base Fortitude or would I add +2, as per the 1st level Ranger?
When you take your first level of ranger, you add what it says in the table. Your BAB increases by +1, your fortitude and reflex saves increase by +2, and you get the 1st-level class features.
animal companions as they gain level they get increased ability scores
Generally, animal companions don't level up. They do get stronger as their master levels up, though.
is there any reason why I would be forbidden to add the scores to Intelligence, thus having a speaking wolf at 20th level
If you were able to increase his ability scores, you could choose to increase his intelligence. This doesn't mean he can speak, however. See this Paizo blog post for more information.