How to cluster dataframe with numeric & categorical data?

Question

My data has numeric column like amount & categorical column like 'payment type' with values cash, cheque & online. I am trying to cluster the data based on these 2 columns. Since it has mixed data type, I tried using kprototype for different no. of clusters and tried to plot an elbow graph to choose the optimal k value. Before trying kprototype, I have cleaned my dataset & removed all the outliers.

Below is the elbow graph I got. Since I cannot see a clear elbow in this graph, I am confused.

below is the code I wrote to get the plot:

# checking k value vs cost function for k = 4 to 9
cst = []
for k in range(4, 10):
    kproto  = KPrototypes(n_clusters=k, max_iter=10)
    kproto.fit(trans_data, categorical=[1])
    
    cst.append([k, kproto.cost_])

temp = pd.DataFrame(cst)
plt.plot(temp[0], temp[1])

Q1: Is something wrong with my code?

Q2: Does it mean that my dataset has no clear clusters?

Q3: Could it mean that my data needs more clusters & I need to plot the graph for higher no of clusters?

Q4: Most importantly, is there any other clustering technique I can use for such kind of data?