Eastwood sells a paint and powdercoat remover for about $22 a quart which should easily do your frame and fork. They also have a rust remover that is gentle on steel and other metals, also in the $22 range. A can of PrepSol or similar pre-paint degreaser costs around $10. That will get you where you need to be to get the frame and fork powdercoated which will cost anywhere from $75 - $150. Make sure that your powder coater knows bicycles and can appropriate mask all threads and other areas where you do not want powdercoat as it is a bear to get off if it gets in the wrong place.

If you go the paint route, I like to use a rust converting primer which I also fog into all my frame tubes. As above, make sure you do a proper masking job first. You can get some pretty decent paints in rattle cans from your automotive body shop supply, but you are better off going to an autobody shop and getting it sprayed and baked with a durable automotive paint. Imron makes some very durable industrial paints, but not all shops will spray it because of toxicity issues during the spray process.