Here are the meanings of these concepts:
Linearity: There must be a linear relationship between the dependent variable and the independent variables.
Scatterplots can show whether there is a linear or curvilinear relationship.
Homoscedasticity: This assumption states that the variance of error terms is similar across the values of the
independent variables. ...
I'm sure the biases are initially initialized to zero but I don't know how the weights are handled.
Looking at the Dense layer docs: by default Dense layers biases are initialized with zeros (bias_initializer='zeros') and weights are initialized with Glorot uniform (kernel_initializer='glorot_uniform').
... "unusual" element to point here; I've ...