Is it unsafe to get tonsil/adenoidectomy & septo/rhinoplasty at sametime only under local anesthesia? airway obstruction/bleeding?

No: That combination of surgery can be done together but not under local anesthesia. Ask your surgeon.

Unsafe: Not only is it unsafe because of the risks of airway obstruction and bleeding. The surgeon would never be able to make sure there was no bleeding as you would be unable to hold still. The pain and pressure in the back of you throat would be unbearable. The septoplasty could be done with just sedation, but not the tonsils.

Bad Idea!: I would not recommend having your tonsils and adenoids removed under local anesthesia. This surgery requires you to be in an extremely uncomfortable position with your mouth very wide open with a gagging retractor in place. Also, if bleeding occurs intraoperatively, you want to make sure that your surgeon is able to establish control most easily without you choking on the blood.