Firstly, regarding the location, I understand that exact location details can be helpful for some investors, but it's my personal preference to keep that information private for now.

As long as one person is a real estate professional, you can usually use rental losses offset joint income.

You're going to have to give a personal guarantee, which means if your LLC defaults on that house they still can recover from you. 

This is basically an unsecured personal loan, like a credit card.

Quote from @Trent Reeve: personally, i would go with the carpet for now. its new and already in.

.- Wholesaling and flipping (which is what you mean by "building", I assume) in the same LLC- Pay all business out of business, pay all personal out of personal.

Gary:Most fair housing discussions I've seen related to occupancy indicate a reasonable occupancy is 2 persons per bedroom. 

Changes some of my answer below, but here would be most of the types of transactions you would have in these accounts and between them.Property transactions would be: all property specific rents and expenses, allocated expense transfer to the master LLC and transfers to master LLC bank account for profit AND/OR property management fee.Master LLC transactions would be: Shared expenses going out, reimbursements/transfers from properties for their allocated share of those expenses coming in, the transfers from your properties deemed as profit AND/OR property management fee and then transfers to your personal accounts deemed as owner distributions.Other transfers that could occur is if the master LLC needs to transfer to the properties for capital expenditures above and beyond the reserves you might leave in their accounts.

Do I need a purchase and sales agreement if I have an off market deal that the person wants to hold off selling till February?

For building a buyers list, I’d recommend joining local real estate investment groups, both in person and online.