hi zedolicious
you might look for welding goggles. they are inexpensive and you can use the glass as a filter in front of your camera. there are a handful of groups
on the interwebs that use these goggles and do very long exposures you might find it a bit cheaper than looking for ND filters ...
with regard to ISO .. unlike the sensortastic cousin you can't really change the iso too drastically. film has a exposure latitude some more than others
and its about a 2 or 3 stop spread without adjusting how you process the film .. meaning you will get something on the negative some of the under exposed
and some of the over exposed images may be a bit more difficult to print than a straight shot. some folks like to always over or always under expose and they
adjust their developing methods to compensate for giving the film more or less light, but still there will be a sweet spot no matter if you over or under develop
over or under agitate, use a active vs not so active developer, don't agitate at all. ... you might experiment with a few rolls on your own to decide what sort of
exposures you like the best ... if you get a 100 foot roll ( sometimes less expensive than the same amount of rolls ) you can roll 12 exposure test rolls
and "bracket" that is change your exposures by full fstops for the whole roll. ( iso value plugged in the camera just tells the lightmeter what to think )
so if you put your film, lets say iso 400 ... expose i frame at 400 and then over expose ever frame by 1 stop after that. do the same thing and under expose 1 full stop
and then develop the film and see what you like. you can do the same thing with short rolls to decide how you want to develop your film too, same stop / iso spread
but change how you develop by 30% more or less time ever short roll. you may decide you like to develop your film under exposed 4 stops ( that would be like insead of
setting your iso at 400 you set it at 6400 ) and sporadically agitated using straight print developer for 8 minutes ..
iso values, and development times are just a blueprint / suggested values you can really do whatever you want // but you really can't vary your exposures by too too much / roll
... unless you want to

have fun with your new camera
john