JF most of your questions have already been answered, but a couple of points need clarifying.

Methanols

Shell offer straight Methanol and a product called Shell A Racing Fuel which is also essentially methanol. I used the latter for years until they decided to price it absurdly. The straight methanol is aviation grade as they supply the airlines who still require methanol for a water meth injection mix. Shell A is essentially 96% methanol with 3% acetone and a purple dye added. The acetone doesn't alter methanol's hygroscopic property. It is there to accelerate flame combustion speed and reduce the tendency for pre-ignition with lean mixtures.

BP Methanol called BP Racing Fuel or some similar marketing euphemism is only 90% methanol according to BP's techical spec. sheet. God only knows what the other unspecified 10% content is now, although the drag racer rumour network mentions upper cylinder lubricants are now included in the BP brew. Note it is not marketed as "methanol". What's in a sausage?

Shell Aviation grade or Shell A is preferred unless you know you're getting unadulturated methanol.

Oils

Straight Castor (or Castrol M) is fine. In NQ you need protection against high temps and lean runs in summer. Castor will offer best protection against this, the downside being a dirtier model, more engine gumming and more rapid internal carbonisation. At $66 for 5 litres, that's pretty expensive for Castrol M. Shop around. You can buy Klotz or CoolPower when they're on promo (regularly) for about the same per litre inc shipping.

Acetone

You don't need to use it, but 2 or 3% does tend to make an engine run observably better, especially in hot humid climes where air density is typically low. Most 'home brewers' don't use it and few commercial model fuel mixes do either. Try without it as like nitro and synthetic oil, acetone is expensive and if you can get away without it all the better.

Nitro

The 46FX is designed for a nitro brew, and will run OK on 5% but best on between 10% & 20%. For sport flying, 5% is fine and will offer easier starting, a more stable idle and easier tuning. You really only need more if you want to swing a bigger diameter prop optimising vertical and engine performance in competition.

Given the price of Castrol M these days, there's little economic benefit gained by using a castor blend over a pure synthetic brew. The FX is a new generation engine and doesn't require a high viscosity oil like castor. Synthetics are less tolerent of an excessively lean run being the downside, their cleanliness and superior lubrication properties when used correctly being the upside. The essential factor is to run sufficient oil no matter what your preferred 'poison'.

Either way mixing your own brew is the way to go from an economic viewpoint in this country. Just remember not to ignore basic health and safety guidelines when mixing. Methanol and nitro are pretty noxious (carcinogenic) and chronic dermal ingestion a serious issue.

Hope all the above assists. Cheers.