A DateTime Item carries the full DateTime. Deep down it actually just stores it as the number of milliseconds that have passed since 1970-01-01T00:00:00.
The label formatting you have in your Sunrise_Time_Hour and Sunrise_Time_Minute only changes how it appears on your sitemap. It doesn’t change the state stored by the DateTime Items. Consequently, Sunrise_Time, Sunrise_Time_Hour, and Sunrise_Time_Minute are all identical.
OK, hopefully confusion #1 is out of the way.
The second confusion is you can not use any of the comparison operations with a DateTime. for what ever reason they are not implemented. In likelihood it’s because a DateTime is really complicated (timezones, daylight savings, different calendar standards, etc.). Instead for DateTimeType you have after() and before methods. See https://www.openhab.org/docs/configuration/rules-dsl.html#using-the-states-of-items-in-rules. Below I’m going to convert the DateTimeType to a Joda DateTime for easier comparison.
Third, if you want the lights to go on at Sunrise, trigger the Rule using the Astro event trigger for Sunrise.
Fourth, put all your Lampe Items into a Group, let’s call it Lampes. Then you can just sendCommand to the Group.
rule "Sunrise - Lights on if sunrise is after 06:58"
when
Time cron "0 58 6 ? * MON-FRI *"
then
if(new DateTime(Sunrise_Time_Hour.state.toString).isAfter(now)){
Lampes.sendCommand(ON)
}
end