---

Thistle you have a lot of questions and many will chime in but here is my 2 cents
There is not such a thing as an inexpensive 13' Whaler, they are very much in demand and therefore hold a lot of value no matter what shape they are in.
You are right about the water/moisture containment/extraction; you'll find many articles on that subject on the net and you can search on this site for more insight.
Personally as a chase boat I wouldn't worry about it.
The 13 will go faster than the Thistle.
Yes you can add steering wheel to a tiller outboard little Whaler.