Additions can range anywhere from $10k-40k or more depending on the contractor, the size of the addition, the style of home, and the finishes you choose. 

Regarding the value of the new property, that will depend on the value of your current property and your loan amount. 

no you can have inspections it depends on the wholesaler 

I was not going to share anything because depending how you look at it.. it was not a success for me at all.

@Luis ReyesA lot of your questions depends on how much time and resources you want to commit to. e.g. if you plan to self-manage, how far do you live?

In my opinion, a 'complete renovation' would normally cost more then 10K per unit but then it depends on what they mean by 'complete'.There are lots of questions to ask and have answered before you can determine to move forward of not;- Statement of work (SOW) regarding work done- What is warrantied and for how longetc.Also while this is not a 'turnkey' as it seems that HW does not own the property, they are certainly intimately involved.

@Dulce Beltran, it really depends on the product that you're looking for as well.

Jun Zao this depends.

Tenants can pay rent online as well as check their account history and balance depending on what you give them for permissions.

To answer your question,1) let me know if this is what you were trying to achieve.The easiest and simplest way to do this is:  - have each property(or few more depending on your risk threshold and situation such as different LLC for different State) under one LLC and have a rental contract for houses under the same LLC, keep a separate bank account and book for this LLC. and repeat the same with other LLCs.