In Farcry 3 does taking outpost affect the number of wild animals

I found a tower weapon unlock list here:

Radio Towers reward you with free weapons and items and they also unlock nearby Supply Drop missions. You’re rewarded with free weapons based on the amount of Radio Towers you’ve unlocked, not by the specific Radio Tower itself. This means that if you want a specific weapon, you can just go for the quickest/easiest route to get there, without having to do a specific tower the other side of the map. The below weapons have been placed into categories along with how many Radio Towers you need to get them for free.

Handguns

• 1911

• 6P9

• .44 Magnum – Requires 11 Radio Tower unlocks.

• D50 – Requires 12 Radio Tower unlocks.

SMGs

• Skorpion – Requires 2 Radio Tower unlocks.

• A2000 – Requires 5 Radio Tower unlocks.

• MP5 – Requires 9 Radio Tower unlocks.

• BZ19 – Requires 14 Radio Tower unlocks.

• Vector .45 ACP – Requires 12 Radio Tower unlocks.

Shotguns

• M133 – Requires 5 Radio Tower unlocks.

• 1887 – Requires 4 Radio Tower unlocks.

• SPAS-12 – Requires 13 Radio Tower unlocks.

Assault Rifles

• AK47 – Requires 2 Radio Tower unlocks.

• STG-90

• F1 – Requires 8 Radio Tower unlocks.

• MS16 – Requires 10 Radio Tower unlocks.

• P416 – Requires 15 Radio Tower unlocks.

• ACE – Requires 13 Radio Tower unlocks.

• Bushman – Signature Weapon. Requires 18 Radio Tower Unlocks

Sniper Rifles

• SVD – Requires 3 Radio Tower unlocks.

• M-700 – Requires 6 Radio Tower unlocks.

• Z93 – Requires 15 Radio Tower unlocks.

LMG’s

• PKM – Requires 4 Radio Tower unlocks.

• U100 – Requires 7 Radio Tower unlocks.

• MKG – Requires 14 Radio Tower unlocks.

Launchers

• RPG-7 – Requires 6 Radio Tower unlocks.

• GL-94 – Requires 8 Radio Tower unlocks.

Specials - Repair Tool – Requires 2 Radio Tower unlocks.

• Flare Gun – Requires 7 Radio Tower unlocks.

• Recurve Bow – Requires 3 Radio Tower unlocks.

• Flamethrower – Requires 5 Radio Tower unlocks.

The game does not give you the direct oppurtunity to have multiple save files for one playthrough, so you will have to go to the "system settings" -> "memory units" -> "memory device holding your saves" on your xbox and then copy the savegame you want onto a different device (e.g. USB stick).
That way you have a backup if the savegame corrupts.
It is a lot of effort but the only way to do it without a modded xbox, sorry.

There are 3 missable things: The achievements "Unheard" and "Fully Inked", and the alternative ending. Everything else can be done after you played the story to its end, as you will still be on the islands.