EEA FM passport return to travel overseas

[caro77]

Hi all,
I'd like to know if somebody is in this situation or if knows how it works.
I sent my EEA FM form on 01/04/2017 and was charged with the fee on 07/04/2017 and yesterday, 2 months later, I received my Case ID but not the letter of the biometrics and not either the COA. Yesterday, I also asked for my passport back hoping it arrives on time for my trip.
The thing is I need to travel abroad for my sister in law's wedding but I don't know if it is in my situation.
I'd like to know if:
Does anybody leave the UK while the application for the residence card is still in process?
Can the application be cancelled or refused if I leave the country?
Coming back to UK, can l get in with my family permit due? I do not need a visa to get in, but there is any problem if I get in as a tourist meanwhile the application is being processing?
Please, let me know if you have any experience about.
Many thanks.
Carolina