Q2(1)
All "10" value cards are treated as pairs, such as J-K, 10-Q etc.
Here’s what I’d suggest.
Always Split 8's and Aces.
A pair of 8's gives 16 ... a really poopy "Stiff" hand. But the 8's individually form the base for much better hands. So ... split them.
Aces should also be split, because individually they can count as 11, and you have a better than even chance of drawing a "10" card to one of the Aces, and you cannot "Stiff" against an Ace.
Never split 4's or 5's. An individual 4 or 5 has too much chance of becoming "Stiff" with one more card.
Pairs of 5's should be doubled, rather than Split (I haven't explained "Doubling" strategy).
NEVER Split 10's. A pair of 10's is usually a winning hand. Splitting 10's, in the hope of turning one of them into a Blackjack, is a weak move, only made by hopeless amateurs, and people on holiday (and day trippers)
Q2(2)
No. A BJ pays 3:2, even if it comes from a split pair.