MTG Salvation

Okay I got a question and i hope i get some help with this. I am running faeburrow Elder in a 3 color deck and i also have perplexing chimera, so I tend to take other people's creatures or enchantments, ect. So my question is would I be able to use other cards abilities with the elder and do I also gain a +1/+1 for them? I know the max amount is +5/+5 among color permanent I color. So technically I gain control of the card. Some people tell me I can only have 3 counters on it cause I'm only running a 3 color deck.