Does marrying a man who only prays on Fridays make me sinful, and will Allah be angry with me, and will He accept my supplications and acts of worship, and will supplicating for him be of any benefit, and when must I leave him, and will this affect our lives and their blessings, and is it better not to have children currently?

It is not permissible for a Muslim woman to marry someone who abandons prayer, as he is considered a transgressor (fasiq) and, according to some imams, a disbeliever (kafir). However, your marriage to him is valid because many scholars do not consider him a disbeliever. Continue to advise him gently and seek the help of his family. Remind him that life is uncertain, and prayer is the foundation of all deeds. Pray for him frequently, and do not delay having children because of this issue.