Sheikh Ahmad Kutty, a senior lecturer and Islamic scholar, has giving a well detailed response on this issues as thus:

“1. As regards shaving your hair in tamattu‘ you are free to do it after `Umra or after performing the major rites of Hajj. There is no hard and fast rule. You may cut short your hair after `Umrah and then shave after the Hajj. Insha’ Allah, Allah will reward you for your best of intentions.

As for tamattu‘ type of hajj, it is true that many consider it as the preferred option since the Prophet (peace and blessings be upon him) had asked his companions to choose it; he also told them that if he were to do it again, he would opt for tamattu‘; he stated that the only reason he did not choose it was because he had brought with him animals for sacrifice. Based on these considerations, many scholars consider Hajj tamattu` as the preferred option; this is especially the case when someone is going to Makkah way before hajj.

2. If you experience a wet dream in Hajj in a state of ihram, you need not worry; since it is beyond your control, it does not invalidate your Hajj; you simply need to perform ghusl.

3. Your desire to purify and cleanse yourself before marriage is a commendable one. You should do so if that is your intention. Hajj, as the Prophet (peace and blessings be upon him) has told us is sure means of cleansing and purification, provided we do it rightly and virtuously, abstaining from all acts of lewdness, obscenities and wrangling.