how do u enter the followers safe-house and whats inside?

Get at least "Liked"-Status with FotA, then you'll get the key from Julie. Read the rest from here

http://fallout.wikia.com/wiki/Followers_Safehouse

its actually pretty pointless in my opinion.

http://fallout.wikia.com/wiki/Followers_safehouse

everything is in crap condition so unless you have stuff to fix with it then it is worthless

I would have to whole heartedly disagree. I've found it's probably the biggest, best collection of loot I have found in the entire game so far. O.o All of it, for what? Donating some extra Rad-Away, Fixer and Med-X? There's like, a metric ton of Med-X you can find if you do Vault 3, even.

Legion one is much better. Lucky Shades, Chainsaw, Legion armor, Sniper Rifle and .308 rounds, Displacer Glove, etc

so is the Brotherhood one. Tesla Cannon, Gatling Laser, Power Armor, Mini Gun, Missile Launcher, etc

and thats just the safehouses. Vault 34 = greatest collection of loot period

Don't forget about the Advanced Radiation Suit. Has 13 DT and only 2 WG. I feel almost guilty using it...

You probably mean the All-Purpose Science suit. It doesn't allow you to wear the 1st Recon Beret, so it's rather useless for me.

Keys work on doors that require a key.
To get this here valuable key please see post #2

Yeah, I have to say that the Legion safehouse is the best for the sole reason of having the Lucky Shades. I always get them even if I'm not supporting the Legion, I have a moment of weakness and console command the lock.