Best program to redraw an existing map?

[Madmaxneo]

Sounds like Gameprinter has already provided you with excellent advise, but since you specified free programmes I will mentions a few things.

1) Are you sure you need a vector programme? If you are just making combat maps for roll20/VTT use then you really don not need a vector-based programme at all. I use vector-based programme for work where millimetre accuracy is key, but raster-based programmes for VTT maps where lighting and atmosphere is more important to me.

2) GIMP & textures: you really don't need to import your textures into GIMP as textures. Just keep them as .PNGs. Presumably you are talking about a Seamless Texture? I never use these but this is how to in GIMP:
-a) drop the .png seamless texture into an open gimp document by drag and drop (or 'import' if you prefer)
-b) scale the texture bigger or smaller based on your needs. It should look like a small square in the middle of the larger image.
-c) take note of the dimensions of your image (not the texture layer!) in pixels. If you can't remember, go to IMAGE>IMAGE PROPERTIES and take note.
-d) while on the texture layer, go to FILTERS>MAP>TILE and bring up the tile dialogue box. Enter your image dimensions and unclick 'new image', then press enter.
RESULT: your seamless texture now fills the entire image. You can delete the bits you don't want but you should really look up jpfrazier's layer mask tutorial and use that instead.

Although this might seem complicate in time you will see it is very simple and much more powerful than maptools.

I think a vector program is my only real choice right now. I have tried manipulating the objects I place in Gimp to match the original image I am trying to re-draw, but it doesn't work well. I also haven't been able to figure out how to manipulate layers in Gimp so that I can create multiple basic shapes or objects and be able to go back and re-manipulate them when I need to.

One thing I need to use vectoring for is setting up a transparent shape, forming it to the shape in the original image, and then filling it with the desired texture. I figured out how to do all that in a matter of minutes in Xara. It took me the better part of a day to figure out how to do a transparency with an image in Gimp, and I still don't have it right as I have been unable to add then manipulate more than one layer in Gimp. Then I have to figure out how to change the shape to fit the original shape on the map.
Right now I have only two days to finish the first part of this project.

Bruce