Yes they are.
spiders
No. A frog is not an arthropod. It's an amphibian. Arthropods are insects, spiders, and other animals with exoskeletons.
No. Spiders are not myriapod. They are arthropod's class is arachnids.
Arthropod is any creature that has an exoskeleton. Arachnid refines that classification to include only Spiders.
Spiders happen to be invertebrates, with a slew of their arthropod kin.
Arthropoda ==> Chelicerata (spiders, scorpions, mites, ticks etc) ==> Arachnida (spiders, scorpions) ==> Scorpiones (scorpions).
Phylum Arthropoda contains spiders, but it is a very broad definition. Spiders can be narrowed down to Class Araneae.
Yes, any insect with an exoskeleton is a arthropod
Some arthropods include insects, spiders, crustaceans, and others.
There are quite a few of these, particularly spiders, tarantulas, millipedes and centipedes.
A scorpion.
Yes, they all belong to the phylum Arthropoda.