Transfer fees for bitcoin

Can someone explain to me how fees work in all this lol I'm new to bitcoin. I want to start buying/selling runescape goods but I got a few questions..
Is it every time you send/recieve from someone you pay a fee, or just when you buy coins from places like coin base? Is it a fixed rate always or does it depend on the your wallet/amount your trading?
Also stuck between wether to use coin base or Blockchain.. Recommendations?

 

When u buy btc u gotta pay fees and when u send u gotta pay fees. Fees doesnt depend on your wallet or amount u sending.
But fees are diffrent on diff sites like Coinbase Block chain i belive Block chain have lowest fees atm

 

Use blockchain & blockchain only.
fee's work on block's, i.e a certain amount of transactions will be confirmed as each block is mined.
depending on how many unconfirmed transactions there are at any given time (found here: 1566 Unconfirmed Transactions ) determines the set fee you'll need. (in theory you can set any fee, but the duration on how long it'll take to process will vary)
Smaller fee's > Slower transactions.
Fee's are in SATASHI'S.
As for the physical fee you'll need to apply, refer to this: Bitcoin Fees for Transactions | bitcoinfees.21.co
as a guide, hope it helps.