I'm assuming you've already ordered, but I hope you haven't. I've made the mistake of ordering iJDMToy LED bulbs before. They are all way too dim. I gave up on using LED turn signals for a while because I thought they were all too dim before I happened upon some generic sounding brand called JDM ASTAR. I swear I have no connection with the company. I installed their LEDs on my Chevy SS and my F30 and they are definitely a bit brighter than stock. They make all the sizes necessary for the front turns, rear turns, brake lights, and reverse lights. They are a bit more expensive, though, at about $20-$35 for a pair. Well worth the price, IMO, as they're cheaper than the "name brand" ones but obviously higher quality and more expensive than the cheap ones on eBay and Amazon. They do have an Amazon store but also sell direct from their own website.
https://www.jdmastar.com/
Let me know if you want to know which ones I got if you haven't ordered them yet.
As far as coding goes, you definitely want to code. Using a load resistor will use more power, require wiring a load resistor, and not even fix the random flashing. Coding is relatively easy if you're good with computers.