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Do I have to use the local wallet for solo-mining, or can I still use the online wallet? This will implicit I've to download the blockchain for a year back, or so.....

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You need to use the local wallet, this is because you are pointing your "UpdaterAddr" to 127.0.0.1, aka localhost. I don't know if it would be possible to mine with a online wallet. (Ask daWallet, Luxe, Blago, etc. They are the ones making the mining programs.) I have always assumed you need a local wallet (Also referred to as a node) to get mining information and to publish your blocks. (Like POW and POS). If you want a fast sync you can download the blockchain from
http://db.burst-team.us. This is one of the advantages of mining to a pool, they are running the local wallet and giving you the information you need.
I'm pretty sure your config is ok, burst's port is 8125 and you need to point to localhost (127.0.0.1 or localhost). I also assume the path to the plot files are correct.

Your miner has to know, and will commit your passphrase on solo-mining. Therefore it is highly recommend to use local wallet, even if remote wallet could be used.
Ensure the passphrase is set correct for your miner. (e.g. for Blagos, passphrases.txt has to be in miner folder.)
Btw. zipped blockchain at
http://db.burst-team.us is ~800MB and updated every 24h. (thx haitch)
-luxe