I am going to install Lubuntu 12.04 as dual boot on a 80 GB HDD (after Win 7 installation 35 GB remained for Lubuntu). I guess it does make sense to create a swap and root partition in addition to a big home partition (But I am not very experienced with Linux). Since the space is limited until I'm able to completely remove Windows, I want to assign a reasonable small root partition. For Ubuntu I read 8-10GB. What size would you recommend for Lubuntu? With 1GB Ram I will create a Swap of 1GB and the rest as Home.
Yes. If you don’t install many apps, 8 GB is enough for Lubuntu. Conseidering that settings and apps user data are stored under home partition, Lubuntu File System takes 2-3 GB at the beginning; you add extra 5 GB for apps and a room for breathing. (Once I myself installed Lubuntu on a 80 GB harddisk, made a 10-GB partition for File System.)
In the case of 1 GB RAM you won’t need much than 1 GB SWAP – Lubuntu itself takes less than 100 MB on startup.
Do not bother creating any sub-partions, they just consume space. During install create only a single root partion and install everything there without swap. You can add swap files as needed later if you really need them (normally you do not).