Is it permissible for a Muslim to slaughter an Aqeeqah on behalf of someone else, and offer it to him as a gift?

In principle, the guardian is the one who should offer the Aqeeqah (the sheep slaughtered on the seventh day from the child`s birth) because he is obliged to provide for the newborn, and it is impermissible for anyone else to slaughter it on his behalf unless with his consent. However, it is permissible for a person to offer the sheep, or its price as a gift to the guardian of the newborn, and then the latter can slaughter it, or deputies someone else to do that on his behalf.

When is Istikharah (guidance prayer) Du`a offered, before Tasleem (saying asalamu alikum warahmatu allah wa barakatuh to end the prayer), or after it?

It is offered after Tasleem.

I suffer from chronic asthma which requires ventoline inhale; which is an air causes the risperatory track/airways to expand. Am I permited to use it during the daylight of Ramadan? And does break one's fast? Noting that I can't go an entire day without using it?

Taking inhaler through the mouth or the nose breaks one's fast, because it is meant to reach the lungs which are part of the coelom. Therefore, whosoever use inhalers for couple of days is obliged to preserve his fasting and make up that day later. As for the ones the ones who need to use it every days are obliged to preserve his fast and feed a poor per day and the cost of feeding one poor is estimated (60) piasters for the year (1421AH). And Allah Knows Best.  

I am a woman, and my natural menstrual cycle lasts six days. In the evening, I perform the testimony (Tashahhud) for myself, and then I engage in sexual intercourse with my husband. After intercourse, I experience bleeding, either immediately or the next day. Is my intercourse with my husband during this time forbidden?