At the moment I am doing the last finishes on the import, that is I am using the validator plugin in JOSM to get rid of as many "errors" as possible in the imported area, and I am eying the end of that as well. The validator throws up a lot that I will not use too much energy on now, and some things that have to be verified on the ground, so I'll deal with only what I can figure out from my arm chair.

Lessons learned can be summed up like this:
1) make short cuts in JOSM before starting on the import, the layer you are working on should have all its necessary short cuts on quick buttons. That also includes quick buttons to erase unwanted tags from the data source
2) get the data sources split in layers, such as all roads, cycleways, buildings, coastlines, etc. if one single layer becomes too large to load in JOSM, split it with an appropriate tool
3) start with updating the coast line, part of the coast line is very difficult to correct if it ends up under heavily detailed areas such as in the middle of a slummish part of the town. (Favela)
4) load all existing roads and cycleways, etc into a file and store it, you will need it if you want to keep the old data and at the same time merge it with the new data. I ended up deleting almost all roads in Vitoria because I didn't do this in advance.
5) The building layer is the largest of them all, do this conversion before attending other data, it is good to have this as a background layer when attending other data as sometimes edges of roads and paths are drawn in building walls. This helps in getting a more complete track data. I think I will try to keep that layer local until the import is completed, that way I can re-update point 4 without the data amount increasing too much
6) Run validator on each layer to get rid of import bugs, such as building not enclosed way. That way imported data will be cleaner and less need for a big cleanup operation after import is completed.
7) Get those names out of the data! The missing text layers are really annoying me. And there so little I can do with it now. Maybe we should arrange a "walking maps" mapping party for Vitoria?

I see on the mailing list of the Brazilian community that Rio de Janeiro (city) and Goiania are preparing similar imports, though they have their source data from .shp files. It looks from the discussions on the mailing list that this probably is much better, as there are more tools to extract and contain the data. My scripts and stuff are too much quick-hacks and semi-solutions. I hope I am able to get data in .shp for my next imports.