I have a few questions that confused me....

1) What´s the difference between "Ne olur" & "Ne olursun"? when can I use each of them in the right situation?

2) How can I know when to use the suffix "i" in the end of some words like for example "seni seviyorum"...what verbs require the suffix?

Thank you in advance...

For suffixes;

http://www.turkishclass.com/turkish_lesson_66

There is no difference between them. You can use both. Just "Ne olursun" is expressing sincerity than other.

By the way, I should say "according to me". Of course you will get many comments about it after while

Çok sağolun