Best company to form for RE Investing
You are right, this is a very wide question, but I will try to give you as many tips as possible.
1. Lets start from discussing Single-member vs. Multiple-member LLC. Generally speaking, there is not much difference in limited liability protection between SMLLC and MMLLC, as long as all the formalities are maintained (such as careful separation of business funds from personal funds). In other words, piercing company veil would be as hard for Single-member LLC as it is for Multiple-member LLC as long as the formalities are kept.
However, as far as protecting your member interest the fact that Multiple-member LLC by definition has more than one member allows it to be structured in a way that would make it harder for creditors to take over the company assets (but its a wider topic outside of the scope of this answer).
2. LLP and LP: those are various forms of limited partnerships, and since you mentioned tat its just you who is involved in this business I would say those types of business entities are irrelevant for you at this point. In any case, it is common to use either LLC or Corporation for business such as real estate.
3. LLC vs. S-Corp: there are certain differences between LLC (that is taxed as partnership or disregarded entity) and S-Corporation, and generally it is recommended to consult your CPA in order to establish which form of taxation is better in your specific case. However, please keep in mind that S-Corporation by itself is a Corporation that was elected to be taxed as "Subcharter Corporation", making it pass-through entity, however this election is not restricted to Corporations, and can be as well applied to LLCs.
In other words, you can form and LLC, and then elect it to be taxed as S-Corporation. Again, in order to make this decision you should consult a CPA, however keep in mind that (with some restrictions) you can generally elect your LLC to be taxed as S-Corporation any time after it was formed (the restrictions apply to how often that can be done).