Is there a rule on how many questions one can ask in a day?

There is no rule, but there is a limit based on your level. You can see that information here:

https://ca.answers.yahoo.com/info/scoring_system

YES, There are Daily limits at every level for how many Questions you can ask and how many Answers you can give.

You are level 4 and to reach level 5, 1,052 more points is what you need.

All the points and levels are here https://answers.yahoo.com/info/scoring_system

Level 1 ( 0- 250 Points) ... can Ask 5 Questions and Answer 20 a day.

At level 2 (250 points) the limits are Answering 80 Questions and Ask 10.

Level 3 (1000-2499 points) you can Ask 15 Questions and answer 120 daily

From level 4 - 7 you can Ask 20 Questions and Answer 160 a day.

Level 4 is (2500 - 4,999)

Level 5 is (5,000 - 9,999)

Level 6 is (10,000 -2,499)

Level 7 is (25,000 plus)

There is not so much a rule but a daily limit. The limit depends on your level/

Level 1:5

Level 2: 10

Level 3: 15

Levels 4-7: 20

Yes. Beginners can ask 5 a day, as they get more levels they can ask fore up to 20 a day.

Yes. It depends on your level.

See this chart. It is based on level.

10 I think