Note: using % instead of * below because I can't for the life of me figure out how to type an asterisk without it being used as an italics markup directive.
>> Given the numerous advantages of int% a; rather than int %a;
Care to elaborate what 'numerous advantages' there are to use int% a instead of int %a, because I can't think of a single one besides 'it feels more natural', which IMO is irrelevant in the context of a coding style.
Enforcing a single line for each variable declaration does not sound like a good idea, in mathematical code this can quickly grow unwieldy due when lots of variable are involved. It also often makes sense to group declarations of related variables on the same line to indicate they are used in the same way, for example 'int v0i, v1i' to indicate two vertex indices.
