It's not in too bad shape, but was a smoker's house and hasn't had any cleaning done in years.Based on a quick walk-through I'm looking at internal painting, minimal external painting, carpet replaced (or removed to get to the hardwood floors where possible), a bunch of minor repairs to things like gutters/eaves/etc.In a perfect world, this relationship would continue to care for the property as issues occur in the future.

I am not sure if this varies but I believe your realtor would know best. 

E - 1/1 $450 lease from 7/26/2006 - Middle aged male likely to continue to stay for an extended time.Taxes on the building would be roughly $2500, Insurance estimate $1200.

That will determine what your offer will be.  70% is not a rule and it varies from 30 to 80 depending on heat.

Do you bill the client (me), or do you allow for rollover if you continue to be engaged for the service until consummation?

Conventional loans don't care how many flips you have done, they care about ability to pay the loan back and the strength of the collateral if things go bad.HML's are usually reserved for experienced investors (exact requirements vary based on the lender). 

You could also release the other tenant from their lease however the problem will continue with the next tenant.In reality you can never correct a noisy tenant issue except by getting rid of them.

I hope to become a more established BP member as time goes on, but until then i will continuously scour the forums for investing tips and tricks!

I've heard too many horror stories in which the investor bought the house, allowed the seller to continue living there (on a lease) and then the seller (now tenant) sued the investor claiming they didnt know they were "actually selling the house".

After that I will be able to use the BRRRR strategy to continue building my portfolio.