Hello everyone, first plan and thoughts

Hi there! I am quite new into cryptocurrencies. I have been reading for a couple of weeks in my free time and I think I am going to get started in the crypto investment world. Here is my plan to do it

Mid-long term investment: I think I am going to use coinbase/gdax for this. I have been reading that with a SEPA transfer from my bank is almost commission free (€) and then you can buy bitcoins that you can transfer to gdax and trade them into ethereum and litecoin. With this 3 currencies I would like to have a 1-2 year investment.
Question about this-> In this platform, can you trade any other currency?

Short term investment -> Bitstamp/Bittrex
In this platform I would like to trade with more currencies as Bittrex offers the opportunity to trade with many of them. My account in bitstamp is not yet validated so I have to wait a bit to get started

I have some questions before going on all this:

- In bitstamp can you withdraw money again to your bank account? Which are the commissions?
- When you want to make a withdraw, do you have to exchange all your cryptocurrency to bitcoin in Bittrex? How is the process?

I think I have the things clear into make deposits but not in how to withdraw them

- What do you think about the plan in general? I am open to suggestions/advices from more experienced people

Many thanks to all