1) If I was late to join jamaat salah for Jumu’a would it be the same rules that apply to any jamaat salah?

2) And also would it be different for Eid salah?

1) If you missed the juma prayer, you would have to do zuhr prayer.

2) Eid salat as well, however eid is recommended so it is okay to enter half way. Juma prayer takes the place of zuhr and therefore must be done correctly.

Entering into any other prayer, a person would have to follow along the imam while counting where they are in the prayer.