It seems odd, but it works. For a while, people believed that the gravity of your wort had a direct correlation to hop utilization, and that boiling with such a small amount of extract in your beer was going to throw your IBUs off. This theory has generally been rejected. You should be fine boiling with only the pound of DME.
If you are pitching liquid yeast into five gallons of beer, a starter is generally advisable. Read the articles at Mr Malty
for the whole explanation of when you need a starter, but I suspect you will want one here.
If you already have a bucket and want to save some money, it is easy enough to rig a blow off tube to the bucket. Just buy a three piece airlock, cut off the small X shaped bit of plastic on the bottom, remove the cap and the floating piece, and affix sanitized plastic tubing to the airlock's inner valve. Run that tubing to a growler full of sanitizer, put the airlock in the bucket lid as normal, and you should be good. This works best if you have extra headroom in the bucket.