Sorry, there aren't really any legal and reliable places to read Spiderman comics for free. You could check your local library though, they might have some copies available for borrowing.
Spiderman's sexuality in the comics is a complex matter. While there have been instances that could be interpreted as bisexuality, it's not a straightforward or widely established aspect of the character.
I'm pretty sure there isn't a Michelle in the Spiderman comics. The comic characters are pretty well-defined, and Michelle isn't one of them. But you never know, there could be a new character introduced in future issues.
Spiderman is not gay in the comics. The character's romantic relationships have mainly been with female characters, which is consistent throughout the majority of the comic series.