ain't that the million dollar question bro?
for both questions, it's basically about being professional, polite, and honest. poeple will respect you even if you don't have much knowledge of the way things work, as long as you give them respect.
If you want to get sponsorship from an instrument company, put together a bio, and a portfolio of what you can offer them - ie. plugging at live gigs, liner notes on future releases, etc . . . if your offer is strong enough that they think it will be of benefit to them , and if they like your music, and if they like you, you may get the deal.
same thing with record companies. put together a professional package and give it to them to look at. be respectful - call them first and ask if you can. find out if the label accepts unsolicited demos (ie. demos that haven't been recommended by a colleague). most major labels only accept solictied demos, which sucks, but they filter through hundreds of artists a day, so what do you expect?
one of the main things is to put yourself in a strong position at the outset. ie. if you come to a record label/instrument company with a strong live following and perhaps a couple of independent releases, you are likely to get a better deal, as you are bringing what they want to the table - a paying audience . . .
o' course, it's much more complicated than that, or we;d all be signed, huh?
but thems the basics as I see 'em