Thank you for your enquiry. I will answer each of your questions in turn.
It is certainly allowed to hire family members under a Sponsor Licence; however you yourself would not be allowed to assign the Certificates of Sponsorship for them. You would need to have a second Level 1 User within your Sponsor Management System, who is not related to you or to your family members, to assign this.
There are various roles in computing listed in Appendix J that may suit the needs of your business, such as IT specialist managers (SOC code 2133) or Information technology and telecommunications professionals not elsewhere classified (SOC code 2139) such as IT Consultants or a Systems Tester.
The Home Office charge £536 or £1476 for a Sponsor Licence application based on the size of the company, and £199 per Certificate of Sponsorship issued. There may also be an Immigration Skills Charge of £364 per year (rising to £1000 per year for large sponsors). The Tier 2 fee would be £587 for an application made overseas, payable in local currency.
Finally, your previous criminal conviction will only have an effect on your application if this remains unspent. If this has not yet been spent, then your application may be refused dependant on the circumstances of the conviction. If this is the case, please do contact me using my details below so that I can assist with this further.