A lot of advice already.
If you're serious, consider the good quality primes (DA or FA limiteds).
If you want versatility and/or want to just try out what focal range/lenses you think you may need, then the kit 18-55 and 55-300 should do just fine. The 18-55 is not going to blow you away, so if you want good IQ from the start, you could consider changing it to the Tamron 17-50 (or DA* 16-50 if you really want WR) or go with the DA 12-24 and Tamron 28-75 combination for more range and versatility (even capable of excellent portraiture in case you even want to go there).
Flash is useful - the Metz 58 or Pantax 540 is the way to go there. Tripod's a matter of personal choice, just go for quality from the start.
Hope this helps.
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