Your body would consume more oxygen yes, but you'd be conditioning yourself under those circumstances so that it wouldn't affect your performance t all, it would more than likely increase your performance. The more muscle you have, the easier things become. Now, start throwing on 50 pounds of muscle here and there then yes, you'll lose stamina. But if you're 135 pounds right now, you could easily add 30 pounds of muscle and not see a drop in stamina. Your body would acclimate to this change and improve.
This is true, but remember keep conditioning your body to your new weight and let it build up over time.
When I first started running track 4 years ago I was 5'7" and 120lbs. I ran the 1600m and 3200m races. The next year I was about 5'7" and 130lbs, didn't condition as I gained weight and had to drop down to the 800m and 1600m. Then last year I was 5'9" and 140lbs and got bumped down to the 400m and 800m because I didn't have the stamina to run the 1600m or 3200m anymore. Now I have gotten considerably faster, dropped my 400m time from 1:08:00 to 0:58:85 in one year, but I can no longer run as long as I used too. As long as you keep working out and staying in peak physical condition then you should be ok with adding a good 20-30lbs of muscle over the span of a year. Don't do it too fast though and remember to constantly condition and work out while your gaining weight so you don't lose stamina.
Right now I'm about 5'10" and 145lbs. I plan to be 155lbs by track season in January, so to keep fit and not loose anymore stamina I'm trying out for the basketball team. Conditioning is whipping my tail at the moment

3x25 reps bench press, 3x25 rep triceps extensions, 3x25 reps curls, 3x45 reps power throws with 10lb medicine ball, 6:00 minute speed rope drills, 290 (6x45) ply-o-jumps, 3x20 sets of dips, defensive slide suicide drills 6 mins, and 400m dashes. That right there is one tough workout.