Well, first of all thanks for all the comments so far.
I've chosen to have all these multiple partitions because I've read somewhere (can't remember exactly where... maybe somewhere in tldp.org or searching some partitioning-specific tip with some search engine) that it is a good idea to do so, especially with /var and /tmp since some bad behaviored app might keep swelling log or temporary files untill it fills up the entire hard drive.
Also, I've read that, sometimes, it is a good idea to make some partitions read-only, like /usr or /usr/local since their content won't be changing (unless updating - installing more apps, uninstalling...) and this may help preventing some malicious intruder from corrupting some system app and implementing some kind of exploit.
About the chosen sizes for each partition... you're absolutely right: it is difficult to predict the required sizes and, of course, even if we do get it more or less right, our own requirements may vary across time - that's why I've exaggerated in setting them with so much available space. And yes, i was intending to use /usr/local for my own developments, in the future.
About using XFS with small files, you're right and i do remember reading exactly that: XFS is more efficient with large files and less with small ones... don't know how I've missed that! Anyway, I'll have to go back and read those wikipedia descriptions of the various file systems so that i can choose one that seems right. I've read something that JFS might be a little less CPU/power consuming when performing operations on files... that also appeals to me - will have to read it again and find my balance.
Then again, i know i might be overdoing it and complicating something that shouldn't be all that much complicated... I'm just installing Trisquel 5 on my 64 bit laptop from scratch, with my hard drive completely clean, and i want to make all the pieces have the best fit all together from the very beginning. You can call me a detail freak, or simply a silly masochist. :)
