A real big ask of your self! A case internal re fit will be a learning curve external leather re fit could be a baptism of fire. Though if you wish to go ahead with the leather re fit find the best you can afford Veg Tanned if poss it develops that golden glow in time. The straps you will want bridal leather also used for the strap retainers and Brass Military roller buckles. Leather thickness 1 to 1.5 mm and sewing machine that is capable of stitching leather fitted with a chisel Leather needle, a walking foot would also be of help for the machine. Now for a more down to earth approach I use a hand cranked 1039's sewing machine use enough force on the crank it will comfortably sew leather failing that a leather stitch marker small hammer and a lot of patience learning how to sew with two needles. Waxed Linen thread is traditional but I feel it is storing up problems for the future it rots so man made fiber is more reliable. Adhesives I used Neoprene contact adhesive for the Leather though rabbit skin glue is more traditional. Now to be honest I have only re covered three leather cases and come to the conclusion that it was like banging your head against a wall nice to stop and not to be repeated. As for internal re fit I have lost count of the number I have done, there are two of my postings of how to do an internal Baize refit one some time back overhauling and internal re fit of an Oak and leather case, the other was an internal re fit to fit a two barrel set into a leather case making the dividers and fitting the Baize. Lastly remove as much of the old leather intact as you can to make the leather templates failing that use heavy gauge brown paper to make them. Take your time, the only things made in a hurry are mistakes and children. Good luck.