When you manage nodes you can add a column for Polling Method. Click the >> on the right side of the bar and then look for "Polling Method" in the drop down list and add it. This will give you how they are polled.
I do this kind of thing pretty often with my clients when they hand me a node list in excel.
My typical work flow is something like col A is the original IP list, I copy paste that into the discovery. You don't normally need to do it 100 at a time, I tend to do them about 1000 at a time, somewhere north of 1000 is where i sometimes run into errors when i try to import the results, depending on the system but I find most environments are comfortable ingesting nodes in batches of at least 1000.
Once the discovery completes and I have done my import I just use SWQL studio to knock out a quick report and copy the output into columns B and C
Select IP_address, objectsubtype from orion.nodes
The object subtype tells me if im polling with ICMP/WMI/SNMP/Agent
Then I highlight columns A and B, use the conditional rules to highlight duplicates then apply a filter to column a and only show cells with no fill. This gives me the list of IP's that are still not discovered, I copy that list to column D
Now add some headers for clarity and I can report back to the client all the nodes we started with (A), what we have found (B), what polling methods are in use (C), and what we couldn't find yet (D). All told the process takes about 5 minutes of my attention, plus however long the discovery takes while I go do some other things.
Since you are using hostnames instead of IP the query could be a little more complicated, I'd do
Select sysname, objectsubtype from orion.nodes
My big concern is always that hostnames tend to be less consistent than IP's