F1 OPT First Year Resident Alien

Hi!

I am on F1 OPT, and I used to file tax through Sprintax as an non-resident alien. Because I first came to the US as F1 in 2018 July, I am determined to be resident alien this year. Since this is the first year that I am filling tax as resident alien, I have two questions:

1) I heard there're some special forms to file out as a first-year resident alien, is there anything else I should fill in addition to my normal income forms

2) I entered the US first time on F1 visa in 2018 July, so for 2023, was I a non-resident or resident alien the whole year, or am I only considered a resident alien after July?

3) My company didn't deduct my FICA tax last year, should I pay the FICA tax to my company or to IRS? If so, should I only pay FICA tax after July or for the whole year of 2023?

4) There's a US-China Tax treaty of non-taxable $5000 income, do I still qualify that as a resident alien on F1 visa?

Thank you so much!!