Yes your wife will need the TB screening certificate.
Does she have an English Language pass certificate ? or is she exempt

Unless you have an exemption, then UKBA are not all interested in what money you have left each month. They only want proof that you have a gross income of £18,600 per year for a couple.
Your payslips and bank statements should reflect this (BTW no payslip below £1550 gross per month sshould be submitted)
You also need a supporting letter confirming financials etc from your employer.