Every-time you complete your highest floor you need to reset. "Do I do the cheapest floor for every course?" I have no idea what you mean by this query. Rushing typically gets more xp but performing all rooms can be more relaxing. That is a personal option. You receive xp bonuses for the amount of creatures you kill as well as the rooms you enter. The number for entering rooms is higher than that for murdering creatures so constantly enter every room but only kill monsters if you want/need to. That is personal question. What do you enjoy doing more? Coaching in a single place or dunging to train many things?
Fractite is your dung equal of rune you are able to use it at level 40. Depends on coaching methods. If doing them using a guide you could probably finish most of them within a day. I'd hazard a guess at around 10 hours play time for everything except that the three you mentioned. Depends on what you anticipate doing. A greater strength is typically used for people that pk/duel. Mage and range can be the same level it will not impact your combat level unless you overtakes your melee combat. Normal - oak - willows is typically the arrangement for coaching woodcutting. I would sell oaks but willows I would burn for firemaking.
Would you want prayer or straight atk/str/def levels? I personally would favor with more prayer so that I would go to mountain giants. After the 40s I'd say hill giants for additional prayer and flesh crawlers as already mentioned. Things won't change much until the fifties when moss giants may be an alternative to mountain giants. Once you hit the sixties you may even consider stronghold of safety spiders.
Alright, so I need most of the fundamentals, I'll post what gear I think and in the event that you could edit it for me it'd be great, and also tell me the approach, I've a vague notion but experience would help. I've 87 Magic, 80 Defense and 83 Hitpoints, if those stats are not sufficient I'd probably train them let me know. Additionally, I am aware soloing rex may entail killing prime and ultimate, so for reference my range level is 79 (80 easily), and 82 Attack and Power. I am mostly doing this for cash, so if rex really isn't decent money anymore/ever that will be nice to understand as well. Thanks.
Let's us to read OSRS gold information on rsgoldfast