Questions about data usage - O2 / Lidl / FONIC

[jennifermehl]

Hello, we are going to be taking a trip to Germany for about 6 weeks. For 10 of those days we will be travelling to Belgium, France, Spain and through Andorra, Italy and Switzerland as well.

I have an old AT&T unlocked iPhone 3GS that we will be taking with on this trip. (Also have an AT&T iPhone5 and Verizon iPhone5, but am thinking of leaving these home if the speed is adequate with the 3GS... less worried about losing it or having it stolen) We will mostly be using the phone for light travel-related data usage, but there is potential for the need to tether my laptop to do something in a work emergency. Also basic phone and SMS usage - to/from German festnetz and mobile phones, and possibly back to US once or twice.

I have an O2 SIM card currently from a previous trip - could I re-activate that on one of O2's current plans like O2 Loop Smartphone Freikarte? Would it have the same phone number? I have been reading that they also offer an EU Internet Tages pack for data roaming that would cover the EU countries at 10MB/day @ 3 EUR.

Alternatively, I am looking at the FONIC and Lidl plans - as they also run on the O2 network do they have the same roaming options?

Who is going to give the fastest data speeds?

We do have the ability to use a German bank account with family when we get there, so would the Lidl/FONIC Smart Tarifs or the regular Tarifs be a better options, to then also add the EU roaming package?

thank you for any info,
Jennifer