Use some aluminum foil to remove the surface rust from chrome.

Yes, the surface must be sealed after using the Fast Etch. The Fast Etch alone will not hold up. We sell this in a kit for such applications which can be found here: https://www.eastwood.com/gas-tank-sealer-kits-eastwood-gas-tank-sealer.html

Safe may not be the question. Remove the self etch at the area of the piece you want to weld

It will only remove rust not stop it. Once you’re finished with the rust dissolver, wipe the surface down with Eastwood PRE Painting Prep to remove any remaining loose rust. Then paint with rust encapsulator

Primer over Primer? Paint and Primer Compatibility Explained. Once dry and sanded, 2K products like urethanes and epoxies can be recoated with products from other brands or systems without any problems.

If the material is able to adhere to bare metal it will work.It will eliminate the rust.

I can only provide the information from the product This specially formulated rust remover is a powerful, rust-fighting liquid created to meet the needs of auto restorers. Ideal Prep for Painting and Powder Coating Leaves Zinc Phosphate Coating Promotes Adhesion and Prevents Rust

Get a quart of white rustoleum oilbased primer (for lite rust) .get sponge style rollers as well. Cut primer appropriately to max amount with approved product.states on label. Roll as much as possible and try to not double coat any areas.cover bed to avoid any rain and place fan or blower on tailgate to speed dry time. Once fully dry use foam brushes to apply primer to missed areas as rolling second coat primer with new sponges.use roller to cleanup and blend any runs or excess from foam brush.apply coat 3 if desired.wait a week b4 sanding for paint and 24 or 48hours(says on can)..AFTER SANDING to apply whatever finish. The sanded newly exposed primer must AIROUT n recure.. <very important. This is the best primer ....most universal with absolute adhesion and durability. Budget friendly and available any hardware store that sells paint. Also R.oleum brush black rust converter paint with half black car frame or something on picture is incredible.very thin product that also brush /roll on And is applied direct to exposed metal.dont prime. Dries to awesome matte like rubber coating that stays where applied...even after years Of tossing concrete tools ..smaller chunks Crete..dirt..gravel. Other products will fail. If desired etch with Muratic acid b4 hand and wash thoroughly After.