multiple DKIM and SPF records

[potschops]

If mandrill use; and verify DKIM and SPF for that domain

It is also necessary to check in Mailwizz?

Because SPF records and DKIM are 2 different companies.
Also, if I use such "mailgum" or other provider, I must add your SPF and DKIM records.
All this can affect deliveries? problems exist ?, records are many records!

 

[Mxyzptlk FishStix]

Just be sure you don't go past the 10 dns lookup limit in your SPF record. (http://www.onlineaspect.com/2009/03/20/too-many-dns-lookups-in-an-spf-record/)
Since you're using Mandrill, signing your emails through Mailwizz is unnecessary. Remove the sending domain.