1) Regular glass will work. It allows you to choose between a negative or positive image in the field. Aluminum is convenient. Just peel and pour. No cleaning. I prefer to use deep purple glass to make ruby ambrotypes. They have a depth and color that can't be matched by aluminum. Making real ferrotype plates would be a pain IMO.

2) Using cyanide fixer instead of hypo gives warmer tones and shorter development times seem to do that too. Addition of silver or potassium nitrate to the developer will make it go the other way towards a more neutral color. I also think some collodion formulas may be slightly warmer due to the particular halide salts used.

3) Artcraft has been mentioned as a source and they have most of what you'll need. Mavidon is another source for plain collodion. Some of the other common photochemicals (hypo, silver nitrate, acetic acid, etc.,) can be purchased through many camera stores or online vendors.

You don't want to make your own collodion as it is a dangerous process involving dissolving nitrocellulose (guncotton) in ether and alcohol. Much better to buy it readymade.