Is Hajj obligatory if one has the financial means but the circumstances are not available, and must the money be spent on Hajj only, and does this fall under a vow?

A vow is only established through words that indicate commitment, such as "Lillahi 'alayya" (Upon me for Allah) or "Nadartu" (I vowed). The phrase mentioned does not establish a vow. If one utters a phrase indicating commitment but then says "in sha' Allah" (if Allah wills), they are not obligated to fulfill it. Therefore, nothing is binding upon you, and you may perform Hajj with this money or spend it as you wish.