1-4:
Just tested the level. I have a few comments that would make the level a bit better.
Good things about the level:
1. For a World 1 Level, the Nipper thing seems to be a pretty neat challenge. I assume an SMWCP coin is going to be in there.
2. I love how falling down the pit brings you to a secret area.
3. The sunset background is great.
Things that could be changed a bit:
1. The level looks pretty empty. I think adding a few coin trails and "?" blocks throughout the level would make it a bit more interesting. Specific areas include the beginning, the area with the triangle blocks, and the midpoint.
2. Add more of a variety of enemies. It seemed odd just seeing a Splittin' Chuck/Charlie at one point of the level. I think one (A bouncing one) should be guarding the goal. I think there should also be another Bullet Bill Blaster as well.
3. For a World 1 level, this is too hard (Picture is below). The jump timing seems to be very hard and along with the "rush" of reaching the "ON/OFF" switch without falling down makes the job harder than it should be. I think adding two more "?" blocks could make this part seem a bit easier.
4. Too short of a level. I know it's a World 1 Level but it just needs an extension. Probably like something else interesting between the Blue/Red Block and the goal area.
I hope my feedback was useful.