I don't have time to go through it all right now, but if you use /hsave, then use /hload, it will load it exactly as it was before.
Assuming you have data in a hash table called Table:
/hsave Table table.hsh
/hmake Table 10
/hload Table table.hsh
... then you'll have the exact same table as you had originally.
As for hash tables, remember that it's formatted as ITEM = DATA. That means that you'd want to do like you suggested and do nick.name, nick.hist, etc. for your items, OR use multiple hash tables...
Data: Nick's Name
Data: Nick's Hist
Having multiple tables will help to make using them much easier. And if you're just getting info on a specific person, you can use $hget instead of $hfind.