Please find below each person's immigration background
1) Working in US. Pending I-485 and valid EAD (Employment Authorization Document).
2) Working in US on H1B.
3) Working in US on H1B.
4) Residing in India.
What type of legal entity (LLC, S Corp, or C Corp) can include these partners.
You can organize your business as C-Corporation or an LLC taxed as partnership. Given the fact your business is online I would say you should opt for LLC since you get all the limited liability protection of a corporation, but without double taxation and without all the corporate formalities. Consider Wyoming or Delaware as the state of formation.
In case your business goes well and you will be looking at the option of doing IPO you will always have the opportunity to reincorporate your business as C-Corporation.