Not sure if I understand correctly. Say I buy coin from Coinbase / Localbitcoins.  If I want to move what I just bought into another wallet, it will be charged?

I also heard when you buy, in general the buy price is about 3% higher than market price.  Same when you sell.  This mean if I trade at 6% higher, it will only be breakeven minus the fee (unless I keep them in the online exchange wallet)?

Another question is, if I want to keep coins in H/W wallet for safety, I have to consider fee and the time for transaction confirmation which is tired to the fee.  If there is a big drop and gain, everyone wants to do the same, the time will take longer even if you choose fast transaction.