You can. In Options, uncheck "Only ask to bid when I have 3 of the same or J9". You'll be asked all the time except when you have 4 nations.

The computer players (AI) will always catch you and 4-ball you.

1. Double - Successfully winning a double with you in particular winning 3 or more hands and claiming 'Double'.
2. Thunee - successfully winning a 'Thunee'.
3. Backside Double - same as double but when opposition trumps after calling.
4. Thunee Catch - catching any opponent playing 'Thunee'.
5. Whitewash - Winnning 12 - 0.
6. Khunuck - You win same or more hands than your partner and successfully claiming a 'Kunuck'.
7. Backside Khunuck - same as khunuck but when opposition trumps after calling.
8. Khunuck 30 - Playing khunuck when your team jodhi is 30 or less.
9. Khunuck 20 - Playing khunuck when your team jodhi is 20 or less.
10. Royal Thunee - successfully winning a 'Royal Thunee'.

4 win 4 lose but 8 if caught by partner.

It's 13 if khunuck was played otherwise 12 irrespective if score is 11-11 or 12-12

No - not by default. But you can disable the corner house rule in options.