Buyers these days really don't want to do any work and they see need windows and siding as energy issues as well as cosmetic issues - everyone is concerned about heating bills and conserving energy. If the exterior of your house isn't up to par with the other homes on the street, that is a negative for people driving by and seeing photos on the Internet; people will make low-ball offers for houses that need work.
The demand for homes at $270K is good - first time buyers are definately buying, but there are 25 houses currently listied for under 300K in Hudson, so buyers have lots of choices; if they are able, they'll pay more to have the work already done. Those who don't have the money to pay more also can't afford to do work.
As to whether you will get back the full $30,000 - that is unlikely, since buyers have high expectations. But I think if you can do these things, it's worth it - you will attract more buyers and the house will sell more quickly - the quicker you sell the more you make; and you can get on with you next move. Also, energy saving items sometimes carry tax credits, and as a seller you may also have additional tax deductions - you should check with your accountant (real estate agents can't give tax advices).
Hope this helps. I would be happy to give an opinion of value - however, no one can predit the future. We do know the better the condition, the quicker you will sell. Marilyn