I've spent a lot of time in the gym over time, especially training for American Football which ive just had to retire from.
working different parts of the body is the only way to work properly, as it will take 2-3 days for an area to recover properly after working out. If you are able to do the same work the next day you are not working any where near hard enough to optimally bulk up.
With regards to diet, my option is to just try to have a reasonably healthy diet maybe just a bit more of it. One of my old trainers said once that with him it didn't matter what he ate as "it was all calories"!