my answer is based solely on my understanding. which isn't much to begin with. bear with me.
1.(Sex before marriage?)
I don't think sex before marriage is ok based on the verses you've quoted about lashing the fornicators/adulterer.in google translate the word is translated as Adulterer not fornicator but this need to be study more in depth.
2.marriage with atheist? agnostic? muslim? in the end it all depends who that person is. for example you could marry an Atheist that doesn't like your beliefs and would prevent you from further teaching the child your views. being an atheist doesn't make a person open minded. nor does being in a muslim society makes a person muslim. Allah knows who and what we are.
angels? as in Gabriel?(Jibreel) I think any person that believes the Quran was sent down from Allah/Creator need to recognise the character Jibreel.
4.Prayer is for our own well being. Contact Allah. so he might reply.
- see my answer above regarding this issue. if it is the command of Allah then we must hear and obey. (this verse needs more reading maybe it does mean "fornicator" rather then "adulterer"
6.I think there is a verse in the Quran that forbids Jews from eating a certain kind of food because it was a punishment from Allah for what they used to do. similarly Allah has a reason to forbid us the eating of pork(maybe it is a test I don't know.. if a thing as simple as not eating a certain kind of animal should hinder a person from his or her deen then... ( )
7.Allah intervene?
it is easy for Allah, the splitting of the sea is as unbelievable to me as there is a giant floating ball of fire outside beaming energy rays to us. yes,I'm talking about the Sun. surely ONE that could create the universe and us humans.. the splitting of the sea would be nothing to Allah the Lord of the worlds.
8.see answer number 7 above ^ "Be and it is"
it is the mercy of Allah that I could feel what I feel. in the Quran it is mentioned that Allah has decreed upon himself mercy. it his mercy that you feel this way and that you were not likened to that of pharaoh. Allah is the Most Merciful if you repent sincerely surely Allah would forgive you but if you turn your back then surely Allah has sent messengers and completed his favour upon mankind.
homosexuality?
Allah condemns homosexual relationships in the Quran. maybe a man could be attracted to another man but according to my understanding Allah has forbidden the relationship.
- (why create humans in the first place?)
All knowledge is with Allah.
verse from chapter 2 verse 30 of the Quran
Behold, thy Lord said to the angels "I will create a vicegerent on earth." They said "Wilt Thou place therein one who will make mischief therein and shed blood?- whilst we do celebrate Thy praises and glorify Thy holy (name)?" He said "I know what ye know not."
12.why did Allah have to create anything? it's a bit hard to answer this question.. even the angels probably don't know. Allah is free of needs. let's study the Quran more. you, me, and the whole of man. let's read.
13.I can't really give a complete answer on this if my memory serves me right Allah does not punish a people until the message has come to them and they reject it while they know. Allah sees everything even our deepest innermost thoughts truly Allah is the best of Judge.
I don't know let's try to understand the subject more Shirk is associating partners with Allah.
- Allah has decreed Islam (submission as the deen of man)
2.people have taken an idol as their master/Lord while it can't do anything for them.. it can't give them nor can it punish them nor save them.
3.Allah sent a Messenger to the people. The messenger warns them. most of the people that reject the messengers in the Quran are either mocking or transgressing or an arrogant tyrant(Pharaoh) or even a people that knows that this is the truth yet they still cover.
- the punishment comes and those who heed the weather forecast about the upcoming hurricane managed to be save while others..
ultimately I would like to say that the examples that I've given is probably full of flaws.. I don't know if I should even reply to this thread.. I do urge you to read the Quran. I hope not to misled others.. so here's a link to Quran Corpus
http//corpus.quran.com/
it has over 7 different english translations I think it is a good site to learn.
http//zombierobots.net/wp-content/main/2011_03/Earth-vs-Sun.jpg
Peace.