Design questions

I am extremely new (and pretty much entirely self-taught) to Access and think
I should give some background to my questions. I'm currently working on a
database (separate to the one I've posted about elsewhere - but similarly
quite confusing!) that will be used to report a rubbish monitoring scheme.
There will be basic data about each country and harbours involved which will
only be updated as and when these change but there will also be waste
tonnages and monitoring data (detailing the number of bits of each kind of
garbage picked up) that need to be inputed monthly. The tables I have thought
out so far a

Country - the info and contact details for each country (only one record per
country)
Harbours - harbour name, number of vessels
VesselTypes - choose from a number of different types (only allowed one
choice)
WasteTonnage - total tonnes collected
Monitoring - monitoring sheet number, number of bags
Plastics - number fields for each type of plastic (bottles, nets and so on).
There will also be a separate table for metals, wood, textiles and so on.

My big questions (I'm working on trying to improve my general access
incompetence but these are driving me bonkers!)

1. I think I need a many-to-many relationship between harbours and type of
vessels (one harbour can have many types; each type can belong to more than
one harbour) but I'm not sure how I go about doing this.
2. Again for vessel types, this is a multiple choice question. Someone
advised me to set up yes/no questions for each type of vessel and then the
partcipant could just choose the correct ones but I read elsewhere to avoid
yes/no boxes. Is there a better way to represent this?
3. Both waste tonnage and monitoring data need to be entered monthly. I'm
pretty sure just typing the month into each of these tables is the wrong way
to go about this so I was thinking I need a separate month table but I wasn't
sure how this should be joined?
4. I've given a separate table to each category of waste but should I
actually only have one table for this? My reasoning behind a table for each
one was that it would be easier to query and get the totals for each section
but I'm very open to any advice about this.

Sorry for the bombardment - feel a wee bit like I'm losing my mind! Any help
would be completely and thoroughly appreciated!