It all sounds normal TBH.
They are babies in a new place. Their house is new, you are new, the sounds are different.
Baby GPs are very fast, have nails like razors blades and feel light they weigh nothing (I've had litters as a child, so have held GPs hours old) 
The humping is normal ( there's a post on here recently about this very subject)
The cooing and purring is them asserting themselves.
There's some good websites about GP aggression. (My 2 had a nasty fight last year- coriander induced.No more coriander)
They've purr round, stiff bodied, purr, like a growling, not a happy short purr.
They might try to push their heads under each other to push each other out the way. Bum pushing or biting.
Things to look out for- face to face, each one puts their head higher until one backs down.
Sitting on haunches, chattering ,grinding teeth. If they mean business they can go right up on their hind legs.
Ours went full on-GP2 got his teeth onto GP1 back- no blood, but we seperated them at night after.
A plant spray is a good way to distract them if they get too full on, but usually they bicker and sort themselves out.
Make sure they have enough space. Space the food bowls and water bottle out. Give them a hidey place each, make sure one can't trap the other.
Eating is a good sign 
And if they wanted to bite you, they would bite you. Ours give a 'friendly' bite but it's usually if they smell food on our skin or if you touch them somewhere sensitive. I've never (touch wood) had skin broken by a bite, but my mum did by one of my old GPs when she was dying- literally hours before the GP died.
Give them time to settle, they are lovely little characters when they get established.We cuddled ours in a towel for the first few weeks, easier for the DC to manage -our pigs were adult,so bigger than your babies and not so fast! And they don't like sitting on skin much, it makes them scrabble their claws to grip. They might not have had much handling in their previous home (were they breeder,rescue ,petshop or a friends GP -Nosy emoticon)
Are they boys /girls?
My adult boars do all the noises, the bolshiness.Pushing each other out of the way.Taking food out of the other ones mouth. Squabbling over the same bit of parsley.
Lots of You Tube Guinea-Pig noises videos as well- they have quite a vocabulary. 