Am I still visible to old contacts I have deleted long ago, when they intall whatsapp if they still have my number in their contacts?
If they have your old number then they are still able to see your old profile.
You are not deleting your profile by simply uninstalling WhatsApp, you need to properly delete your profile by going into Settings-&gt;Account and select Delete my account.
Then your old profile is deleted and nobody will be able to see it or send any messages to it.