Puerto Jimenez is quite small and not really much you can do. The weather is hot and humid so ideally try to get a room with aircon. 

SLEEP
We did not book in advance, just went there and as we checked some places to sleep before we arrived and went to Cabinas Marcelina. 
We booked a 2 bed room and added an 3rd bed inside as it was cheaper than the triple room (online the triple room was 55$).
There is hot water, wifi & aircon available. I would say it is a good place to stay for the night.

FOOD & DRINKS
Restaurants, we checked Trip Adviser. Had dinner at Marisqueria Corcovado which is just next to the port. For the place I guess it was good,fish was fresh and service ok; if I compare it with other fish restaurants around Costa Rica I would say this one is average. 

We did not have lunch instead we got inside a bar had some Imperial beer (as I preferred it to the Pilzen) and we could 'order' some chicken wings from across the street. Watching Champions League and later one some Latino music on the background. 

The nature, scenery & wildlife are absolutely amazing and it gives you the chance to be for a while alone with the nature. 

There are several tour options and starting point locations so depending on your time, money and preferences you can pick. I'll give you all the details of our trip. 

We booked a 2 days (one night) trip.
Entry point Puerto Jimenez (Carate)
Exit point Drake Bay

I'll list below the 3 ways we checked to get to Corcovado (same will apply to get out to those locations). 

1. From San Jose
2. From Manuel Antonio 
3. From Panama

You can either fly to Drake Bay or to Puerto Jimenez with one of the 2 local airlines.
- NatureAir
- Sansa 
Or you can catch a bus
- to Golfito with Tracopacr 3 buses per day with 7 380 colones (+ a boat that is 6$ per person)
- to Puerto Jimenez in shuttle bus 89$ leaves at 5AM