Killarney hints

Hello, r/irishtourism.

I am planning a two week long drive across Ireland this autumn and hesitate in choosing Cork and Killarney as a place to meet my 30th birthday. After some consideration I picked Killarney, but have some questions about it:

• How crowded Killarney usually is in mid-September?
• Good places to eat in the city? I'm not looking for something fancy, just wishing to have a good meal.
• Are there any good pubs to get my birthday pints? Good selection of non-major beers is preferred.
• I am thinking about hiking around Killarney lakes to fight the next day's hangover . What do think about this idea?
• Actually, is preferring Killarney to Cork a good idea?

Thanks in advance for you help!