Thanks!

For the #1, I've read 16F1829 datasheet, and it says that it can emulate 555 timer in hardware, so I guess, it might be possible to do what I want.

For the #2, I see this In the following way:

Interrupt was set to rising edge, it happened, and code is launched, which does what it should do, in loop. Same time, interrupt type is changed to falling edge, so when signal on interrupt pin gets low, code is terminated and main code execution continues. This is what I want to do.