Sure, Applying together is a better idea for a variety of reasons - including the fact that mostly either entire file is approved or rejected altogether. Plus the actual person needed / offered study in Canada might base his decision upon that (e.g. i won't have considered coming here for a second, if any of my family members was denied).
Principal applicant is the person needed for some reason in Canada. Others are liabilities.
Regarding your question, sure by all means, you can give him money. In fact if you show your income as source of money, i feel it might serve as one evidence of relationship.
Other than that, you could add any thing to support relationship. For instance this is required for people who are in common law (not married but have been living together for at least 1-2 years). They submit documents like bank statements of each showing the same address, phone bills, car lease in joint name or still other things showing common address. Because you cannot be common law if you haven't lived together for (1 or 2) years i think. This is not needed for a married couple, but one or two evidence of this sort would strengthen the case. Say showing you have lived together before your move to Canada. You might as well submit pictures. But those are usually more relevant when the principal applicant went to home country for a short time, got married and came back. Then they have to show the marriage was genuine and hence use pictures, wedding cards, honey moon tickets etc. For a person in your position, you might not even have those (i don't). But still some pictures could help.
Personally, i don't like sending pictures - and avoid that if possible. But that's me.
