Does a history of a couple of sunburns and occasional tanningbed use over 10 years ago put me at considerable risk of melanoma developing in my moles?

More than without: It may not be considerable but your risk of melanoma is higher than what it was before exposure to sun burn and tanning booth. You should examine all your mole, or have a trusted person examine those, once a month. Taking pictures will help in comparing. If any lesions grow in size, become irregular, nodular, ulcerate of bleed, see doctor. Consult this site for info http://www.webmd.com/melanoma-skin-cancer/skin-self-examination