How to get to Twine Peaks after the new Canny Valley storyline

I can't give you exact details on their percentage boosts but each tower provides a boost to your entire team when you deposit the BluGlo. Health increases your health regen, movement speed boosts how fast you run, building boosts how quickly you build things etc, they're fairly self-explanatory.

For the most part they lasted for 2 minutes as far as I remember.

Every mission (other than storm shield defense) has a time limit, with some being longer than others (I believe the longest non-event limit is 4 days for a Protect 4 Atlases mission). This is to prevent people from afking in an instance of the game world forever. By using time limits, it also encourages players to work together to put together strong defenses quickly instead of solo-grinding resources and loot.

Fortnite is not meant to be a exploration game. While some discovery is necessary on each map (to find objectives, locate secondary targets, etc.), it is primarily a base defense FPS. Besides, once you've seen one map, you've seen pretty much all of them. They are all extremely similar.