Income is figured before retirement contributions.
W2 salary is prior to deductions.
Schedule C is similar.
Generally if you own more than 25% of a corporation, the K1’s & 1120S are required to be submitted as well as 1040’s
Most approvals are automated. Very rare to have manual underwriting now. Maybe some exceptions.
I don’t think that many institutions hold many loans for 30yrs these days, 10yrs or less perhaps.
HELOC’s do not have the same risk exposure; usually tied to the prime rate.