Hummm this is a strange one and your going to get some poeple that say yes its a good idea to mod first and some that will say no your wasting money modding just jump into a full build
i can only recount what ive learned sofar
Im just about done building my first ever bass which is a singlecut headless 6 string
I like yourself had GAS for a new bass for me this was in the form of a headless 6 SC of my own design but when i did the rounds of UK builders with my wants list it soon became clear that id have to spend around £2000 (about $4000) give or take a few hundred pounds to get what i wanted
upon checking a rechecking the prices on woods and hardware i found out that even after importing all my woods from the US (i just could'nt find a UK dealer who stocked zebra in the thickness i wanted) and most of my hardware the cost of my spec's came in at around £350...humm £1650 saved if i do it myself thats to big a saving for me not to want to try and do it for myself worst case i mess up and still have hardware another buillder can use for me
So i did some reading and a little more reading brought a few books read somemore ask a few question here on LC and decided it was well within my ablities to have a go and see what happened
Ive taken my time & sofar it gone very well and i like you had Zero woodworking experience before i started this build(unless you count the last time i use any woodworking tools which was about 17 years ago in secondary school)
Ive had todo all the things you listed in your mods list(and a few more) the only diffrents is my wood didnt come pre-shapped most of the tools your going to need to do the things you listed like body work,neck work and other modding jobs are also tools you can use to do a build from scratch
Have a good read of the forums here & dig back a few months you'll see many first build threads and these may help you in deciding if you fancy just jumping in a the deep end or if your safer paddeling in the shallows for a while
What ever you do im sure you'll enjoy it,i have to say sofar building my own bass is one of the most rewarding things ive done and i have definitely got the build bug infact builds 2 & 3 are in planing now and i cant wait to start them
Good luck with what ever you decide todo
Cheers
Thonk