A. BulkPing.com Ping all Url's from Serverside i.e. mysql based because it has to be run via private proxies. Ping Sites who do it fast do it on browser side & its not effective & ITS IMPOSSIBLE get successful results by PINGING even 100 urls with same IP to engines (They are SMART).
A. UNLIMITED, YES you read it right Just upload domains in text file and u are done, will take few mins to few hours as per Queue or Proxy available. We got bunch of 2500 Private Proxies from 12 Countries.
A. BulkPing.com runs on 3 Dedicated Servers i.e. 1 is for script & 2 for mysql and submisisions (known as beefy server).
A. We do SEO for Few Big portals and sites and daily ping our own 50,000 URLs thats why weve made this site BUT as our servers are Free most of the time we made these tools public.
A. We Suggest to use all 3 tools to ping ur site specially create and submit RSS daily with random links also ping it too and repeat Pinging + fast backlink tool twice a week,on Ist ping itself Bots crawl sites in few mins but for indexing Google or yahoo use their own algorithems so it may take time
A. When server get disconnected from your browser or PC or timeout it shows these errors, BUT you need not worry once the files or pasted URLS are uploaded submisson start in backround on server.