I need some advice on an offer

[Nick Ferguson]

So I just looked at a house with a lot of potential and I would like to make an offer.  It may be an offer that will not be accepted because of what I will require before closing but you will see that.  Here is the situation and then a few questions. 

It is a duplex listed in the mid 60's.  The house currently has tenants paying a total of 1300 per month.  Current owner has had the house over 5 years and it has some significant deferred maintenance but none of the traditional red flags like structural/foundational issues etc. I wasn't able to look at the roof in detail because of snow but from what I could tell in the spots that were visible, the roof is old but in decent shape. 

Problems #1.  The house has wood siding that definitely needs scraped and painted.  As I have never dealt with wood siding, what is everyone's experience with it?  My realtor stated that it was more costly to take care of wood siding which does make sense.  

Problem #2.  There is a garage that is in serious need of repair.  The roof has holes in it and it looks to be leaning.  I think it is quite obvious that it should be knocked down.  The current tenants don't have garage access so it wouldn't hurt rent rates.  Any drawbacks to knocking down the garage and NOT replacing it for a rental duplex?

I'm thinking of offering at or slightly above offering price contingent upon knocking down the garage and scraping and painting the siding.  What are your thoughts in general?