Wow ... Loads of questions there ... Firstly whenever working with partitions PLEASE NOTE you could LOSE all your data. So you need to be extra careful. However after taking that warning into account this is possible.
Is there anyway to partition part of the windows hard drive for Ubuntu use?
You can use GParted in Ubuntu to resize your windows partition. Although you do not necessarily need to resize the partition to use it. You could just mount it from inside Ubuntu and have access to it whenever you need it. That way any data you add to that drive is available in Windows as well. this is a good idea if you use this drive for data (documents, pictures etc).
could I combine free space on the other hard drive with one of those so it could still > be accessed in the same way but with more memory?
Adding extra drive space to a partition has no effect on memory. Perhaps you meant can you add space to e.g. /home so it is bigger and then can hold more data. If that is the case then you can do this with some file systems (zfs) however I hate fiddling with file systems like this and typically start from scratch and just start with the partitions being the correct size.
Should I combine / and home since I am only running out of memory in / ?
Again I assume that you are referring to disk space and not memory. I would not combine / and /home as this has an impact especially if you want to re-install later ... with a separate "/" partition you can simply install Ubuntu and format / but you can keep your data safe in the /home partition. Although if you are experiencing space issues then you may want to look into resizing your partitions using something like GParted.
Would any partitioning affect the boot of windows since the boot loader is on that drive also?
That depends on what changes you make to the boot partition. If you just resize it it will still boot as before. however there are flags that can be changed that will effect if that drive is recognized as a bootable drive or not. I wouldn't change anything like that though.
It sounds to me as though your system has grown over time and could probably benefit from re-installing both OS's but this time do some planning before hand and work out what space you will need for which partition.