Terumot & Ma’aserot

I picked about 10 avocados last week and brought them home. Do I have to wait till they are soft and tasty to separate terumot and ma'aserot? I think you can eat them unripe though they are not tasty. 
But if I cut an unripe one for terumot and ma'aserot, I will have to throw away part since once cut,  avocados no longer ripen.
Also what do they do in supermarkets where terumot and ma'aserot have been taken but the avocados still need a week or 2 before they ripen and can be eaten?

I live in the Old City in Jerusalem. What do I do with my ma’aser sheni?

Loquat and almond trees bloom early, some before Tu BiShevat, and some afterwards. How do I take teruma and ma’aser from these fruit?

How can I actually give my ma’aser ani? It’s not really practical to find poor people each time I pick a few oranges from my tree to give them a slice.

 My question is as follows: Does the rule of “seeing the inside of the house,” apply to crops grown in a hothouse, meaning that it would it be forbidden to snack on fruit or vegetables in the hothouse without first taking teruma and ma’aser?

During the shemita year, we heard that many poskim view hothouses as a house for halachic purposes.

Loquat and almond trees bloom early, some before Tu BiShevat, and some afterwards. How do I take teruma and ma’aser  from these fruit?

If I buy grapes or olives from which terumot and ma’aserot were taken, and then use them to make wine or olive oil, do I need to take terumot and ma’aserot again (at the completion of the process, gemar melacha)?