mtg all samurai cards it gains lifelink until end of turn Subtype: Samurai, Colors: Green, 7

That should be all you need to do

May I suggest Goblin Cannon, Rocket Launcher, Fleetwheel Cruiser, Goblin Charbelcher, Jade Statue, Phyrexian Processor, Time Bomb, Wand of the Elements, or Whirling Catapult instead

Yes, if you want to buy a booster box and its in your budget, go for it

That puts it in junk Rare territory with Astral Cornucopia (XXX, Astral Cornucopia enters the battlefield with X charge counters on it

If an effect allows you to put a card with particular characteristics onto the battlefield without instructing you to play or cast it, consider only the characteristics of a modal double-faced card's front face to see if that card qualifies

Be very careful with adding in more entering tapped lands as you are already running a lot of them