I do not quite understand this sentence
Payment Request will start at 10000 Satoshi and incremental for each Payment Request as 20000, 30000, 40000, 50000. and will be at 50000 Satoshi for the rest payment.
It turns out if I output 10k
Next time limit for the withdrawal of 20k?

yep you're right first time you can request 10000 satoshi and will be paid to you, next your withdraw threshold will be set to 20000 satoshi and so on.
your withdraw threshold will be set to 50000 satoshi at 5th withdrawal request and will be same as 50000 satoshi for the every request thereafter.