1.) In short, Yes on most of them.
On many exchanges you can trade with FIAT money. FIAT is just term for currencys like €,$, etc.
Deepending where the exchange is located you can exchannge usualy us$ and YEN, Rubel,NZ$ what ever.
Also most of them support credit cards, SEPA and diiffrent payment method may vary.

2.) Yes it is possible to keep money and coins on most of the exchanges. There are some exchanges where you don´t store any coins, like changelly for exmaple, but they are the minority.

3.)With FIAT money the day should differ deepending on the location of the exchange. Usualy the same time a normal bank transfere takes fom, for example, asia to your destination.

Better put some time in research about diffrent exchanges. There are big differences in the fees, amounts you trade and identifikation prosses.
Some times it is nerv wrecking, when you are looking for a quick start, nothing goes quick.
But better take your time now then getting in trouble when it comes to payment terms.