It really depends on your market, time of year, peak vs non peak, holiday or special event etc.I only use 2 day min during offseason or for orphaned days.

The group collectively contributes the down payment, closing costs, reserves, and reno $$ if applicable.

It's not my place to tell anyone how much risk to take, but non load bearing walls by a good licensed contractor isn't something I'd worry about too much.

Right now I have 75% at 7.5% Fannie/Freddie will only go up to 75% on a single family non-owner, so to go up to 80% you have to use non-QM financing which is going to be higher rate then fannie/freddie.  

Does anyone have any suggestions or pointers for a Credit score, lenders/broker, location, down payment amount (15%?)? 

This applies to properties used for the production of income, such as rental properties.However, if you initially declared your property as an STR (which typically falls under different tax rules), you might have been using a depreciation period of 39 years, which is common for non-residential property or property used for personal purposes.When you convert your property from STR to LTR, it's considered a change in use for tax purposes, and you would adjust your depreciation schedule accordingly.

Paneling is easy to pull and in this case trying to match is a non-starter. 

I was thinking out of the down payment (Increase down payment by my fee amount and reduce the purchase price by same amount). 

:)  You will want to do both A and B. you will want to save enough for a down payment and enough in cash reserves for a rainy day fund.

And request payment within 10 days to avoid legal ramifications.