The pregnancy process is really weird. But one thing is simple: the spermatozoids are very sensitive, they die because of everything. But if after the first days you tried it and it came out negative, it doesn't mean you're not pregnant, my advice would be to try it again, just to be sure of the result.
Not usually. You have asked a lot of questions this week about being pregnant. We have told you that it is probably too soon to check. If you miss your period in a few weeks, take a test then. I don't mean to sound harsh, but I really wish you would be this concerned about using protection and birth control. You are clearly very nervous about possibly being pregnant now.