From past experience wouldn't use any other gaskets bar oem one's but it's up to you. Yeah local hardware store still not the point if they stated it came with them let us know how you get on
You can reuse the top nuts they just screw back on you will know when you take the cat off just buy 3 bolts/nuts to connect to exhaust in all honesty I would buy new genuine toyota gaskets and wait for td to send them rather than rush tomorrow sort of thing up to you though
6000's enough imo there really bright I only paid £25 for mine, been spot on so far just ebay's thought I'd try cheapo's and was very surprised! My mate paid £130 for his had nothing but problems!