Multiple LED panels?

I used 3 of the panels to upgrade an outside light, more lumens and still saved a bunch of watts. Just parallel till you get what you need.

WDP

Take those lumen ratings for LEDs with a grain of salt. I converted my entire MH to LEDs about 2 years ago. Read about it here. Most 48-3528 panels will NOT put out more light than an 1156 incandescent. If I were you, I'd go with 48-5050 panels (5050's put out about 2X the light output of 3528 LEDs). I used 48-5050 panels to replace my 1141 bulbs; they work well, but are just slightly brighter (and 1156's are already brighter than 1141's). Also keep in mind that the color temp affects brightness also; with warm white (+/-3500K) putting out less lumens than bright (daylight) white (+/-5500K).

Yes, you can. I did exactly that on my exterior light. Two panels fit exactly in there. I had to splice the wiring together and shim up one end of the light housing with a layer of double sided foam tape (wasn't flat). The stock 1156 bulbs are about 400 lumen, so one panel is already brighter. One panel is plenty for interior use, but I wanted a nice bright exterior light (usually use the color changing LED strip under the awning so as not to be obnoxiously bright when not necessary).

I am not sure you will get brighter but will definitely get more efficient. I did 42SMD soft white round to replace my 921 bulbs and the lumens were 1/10 the incandescent. That was not really an issue for us as we do all our reading on backlit ebook readers and tablets anyway, and we preferred it not being as bright as an operating room. I would definitely get the flat LED's and get them in bright white if you want brighter. Some people have indicated that good brand name bulbs are brighter than some of the cheap ones off eBay. Even with 2 you may still be less bright than the original bulb though.
I did a full write up of my experience doing the LED upgrade with detailed brightness testing.
https://rwbradley12.wordpress.com/2015/08/24/led-light-upgrade/

Led draw about 1/10th the power. You'll be OK

A quick google check shows the 1156 draws 26w.