Hey,
Is Stratis similar to XEM/NEM in terms of staking?
I can keep coins on my wallet (offline) and get annual fee's?
If so, how much minimum coins needed?
You can stake STRATIS by keeping your coins in your QT wallet,but you need to keep the wallet online to stake. The PoS rate is 1%/year. Good luck!
I don't know where you're getting the 1% inflation rate but I don't believe that's true. The rewards are 1 STRAT per block, with each block produced every 1 minute on an average. Based on the current supply, this gives a less than 1% inflation rate for PoS.
Sorry,that's my bad.. 1% was the inflation rate some while ago. As @ruletheworld said the rewards are 1 STRAT per block.

I am looking to steak coins with the STRAT wallet, if I have 7000 STRAT what sort of returns am I looking at?
You can use the calculator here:
https://stratispool.com/ to get an estimation. You should get around 8-9 STRAT per month.